After much trial and error I think I've found an efficient way to calibrate your 3D printer and quickly tune for different filaments. I've done several 2A prints after doing this and haven't run into any issues with mag fits or parts not fitting together properly. I figured I'd share my methods to help those who already have 3D printers or those that might be getting their first one this Christmas. When I first got my printer I spent hours trying to get it calibrated and seemed to never really get it where I wanted, but now I have an efficient process that gets me dialed in without much headaches.

1. First thing first you absolutely need to calibrate the extruder esteps (marlin) or rotation distance (klipper). I find this print helps to take some of the inconsistences out of using calipers. https://www.thingiverse.com/thing:4108156. Use those scraps of filament you have laying around from partial spools for this. Run the test about 5 times to ensure you have it dialed in. Good news is once you calibrate this you don't have to touch it again even if you change filament types. Teaching tech has a good guide for calibrating esteps https://teachingtechyt.github.io/calibration.html#esteps

Follow this guide https://github.com/AndrewEllis93/Print-Tuning-Guide It may be for more advanced users, but the first few sections are very helpful no matter what printer you use or your 3D printing skill level. Previously I used TeachingTech's methods, but I've gotten much better and consistent results using this guide instead.

2. In the guide linked above it shows pictures of what your first layer should look like. That's related to bed leveling and your Z offset. This guide has STL files for bed leveling patches. I place 9 patches evenly spaced on the bed and use the ones for the first layer height I'm using. Larger layer heights are easier to get dialed in beginning out.

3. If you want do your temperature towers here, but I skip this step and use the higher end temps for the filament I'm using. You can tune temperature in the retraction calibration test further down.

4. If using Klipper you would now calibrate pressure advance or Linear Advance (Marlin). Some Creality 32 bit boards don't allow Linear Advance calibrations. You can skip this step if it seems too advanced for you, but there are guides out there. Klipper makes it relatively easy. Always lean towards the smaller value for these. Too large of a value causes more issues than too small. This is what gives you nice crisp corners without bulging.

5. Now you must calibrate flow. The flow rate you use will change for every filament you use. Maybe not between each roll of the same filament, but definitely between brands or different filament types.   Some filaments I have set to 1.06 (filament diameter ran small) and higher quality Esun PLA+ (0.97). You will be doing this section the most and most likely for every filament brand/type you use.

To quickly calibrate the flow use the flow cubes in the guide and follow the guide for the slicer settings. They are already labeled and in you slicer Cura/PrusaSlicer/SuperSlicer you can change the properties on each object. In your slicer change the flow rate on each object to match what the flow cube is labeled. I usually test 90%-110% in 1-2% increments. You can then narrow it down in 0.5% increments if you want to go that far. See the pictures in the guide to get an idea for what you're looking for.

Pro tip after calibrating your flow you may need to adjust your Z offset again. If you initially set it when the slicer flow rate was set to 100% but you found after calibration your flow needed to be 95% then you're extruding less plastic and may need more squish or less if you had to go higher on your flow rate.

6. Now move on to retraction calibration and the best method I've found is this guide http://retractioncalibration.com/. It's a very quick way to test many different retraction values and different temperatures all in 1 print. Bowden tube users will be in the 4mm-6mm retraction range and direct drive will be around 1mm retraction.

7. Support settings. 3D Print General Youtube has very good settings to get your supports dialed in. He's recently added another video that may be helpful as well. 3D Print Pew General Supports.. These were very helpful when I was tying to get supports that were good, but also easy to remove from the print.

8. Now that you have everything calibrated save this profile in your slicer. If you change nozzle size you may need to run the flow test again. So, be sure to save by filament brand/type/nozzle size.

Other Tips
1. Don't go cheap on nozzles. Sure you can get a multi pack of nozzles cheap, but I guarantee the cheap ones don't have the proper hole diameter (or consistent) and they aren't the same overall length between each one. If you don't have the same hole sizes all that calibration you just did would need to be done again when you change nozzles. If the overall length varies you'll have to adjust your Z offset every time you change nozzles as well. There's no telling how much time I wasted getting every thing tuned again from using cheap nozzles. It's just not worth it. I use the solid copper nickel plated Trianglelab nozzles Trianglelabs. I can switch between 0.4mm and 0.6mm nozzles and not have to adjust my z offset. My flow rate calibrations for each nozzle size stay the same. I also use one of those wheeler torque screwdrivers you use for working on guns to tighten the nozzles to the same torque each time.

2. Absolutely get auto bed leveling. This just saves time and helps with the overall 3D printing experience.

3. Get a magnetic PEI flex plate. They're just worth it. I also print on the Creality glass surface, but for ABS/PETG prints PEI is much better.

4. Hoffman Tactical has good videos on some of the settings he uses for 2A prints. One of them is how thick of a line you should be printing. I print at 125% of nozzle diameter. You'll find most 2A prints they say print at 0.4mm same as nozzle size, but for stronger prints you want to go wider like 120% of nozzle diameter. The new Cura and PrusaSlicers will vary the line diameter to best fit the model. You can still specify thicker for infill and outside wall make same as nozzle diameter. I think this is an area in 2A prints that could be researched more. Hoffman Tactical 2A Print Slicer Settings

5. Tension your belts properly and consider replacing the wheels with linear rails. With linear rails you only need to worry about belt tension not now tight you get the wheels. One less thing to worry with.

6. Creality stock hot ends will eventually have issues. CHEP shows what the fix is and I recommend doing this even with brand new printers. CHEP Hot End FixI'd look to better hot ends for replacements later. Micro Swiss is kinda dated, and I'd look to Trianglelabs for hot ends. My next hot end will be their Rapido hot end.

I got rid of the crappy springs and made custom mounts for my bed.  It is absolutely rigid.  I leveled it nearly a year ago with BL Touch and haven't touched it, and I have no need to touch it.  In fact, three nights ago the fan on my hot end failed, not the small one that cools the filament, but the one that cools the heat sink.  I got on the floor with it, flipping it this way and that way to get to the motherboard and to replace the wire, etc.  I still didn't check the level, nor relevel.  It is printing Ivan's 3011 right now as I type this.  My mounts are flawless.

My experience with a magnetic PEI flex plate rendered my printer useless.  I bought it from TH3D Studios and it was absolutely a POS.  I got no help, assistance, or refund from them.  I might take it to my range and make a target from it.  I went back to the original Creality bed that it came with and have had no issues.

My experience for the proper fix for a Creality hot end, and others of that design is a bi-metal heat break.  I installed a Slice Engineering Copperhead in my Ender 3 v2.  It has direct drive, but it still uses the same old crappy design that puts the tube against the hot end.  Mine melted and caused several clogs before I figured it out.  Now, many months, and many prints later, and printing at 225 degrees it has not failed once.  I've not had a single clog and I have not replaced the short piece (about 1
.25" long, more or less) of tubing that the direct drive uses.

I also got rid of that terrible Creality firmware and flashed Jyers UI.  It's free and it's like getting a new printer.  This would be a must-have for me.

I'm not touting these as absolutes, these are just my experiences and what works for me.

I've done pretty much the same with my yellow springs, flipping the printer all about, but level stays and the ABL takes care of the z-offset.

I've had great luck with the Wham-Bam Flex sheets, in both PEI and PEX.  PLA, PETG, ABS... all have been no issue.

Also, never used Jyer's UI (don't think it's available for the Pro), but did use my personal branch/compile for a while... And the upgrade to Kipper is so much better - I'll never go back to Marlin!

I use the silicone spacers instead of springs.

Klipper is so much better than Marlin. I hated compiling Marlin and flashing the firmware for minor changes.

I'm running the Dragon HF hot end on my Ender 5 and will probably upgrade to the Rapido in the future and put the Dragon on my Ender 3.

Lots of people recommend the Micro Swiss mainly because it's a direct replacement for the stock Creality hot end. However, it really doesn't offer much performance over the standard hot end other than being all metal.

I have considered Klipper, it certainly seems like it is a better firmware.  But gee whiz, it looks very involved to install it.  Maybe one day I'll try it.

BTW OP, good thread.

I was worried about the same, but finally took a day to install and setup... Used MainsailOS, and install was super easy, and calibration was not difficult at all.

Tuning is fairly involved, but this guide walks you thru pretty well.

100% recommended.