I've heard some people just soak the entire BCG in cleaning fluid vs. disassembling it and cleaning it that way...My Saint Edge Pistol I've chosen to break the BCG down by turning the piston retention pin so I could remove the piston and the pin.  I also used needle nosed pliers to pull the firing pin cotter pin out.  I then used brushes and cotton Q-tips and patches to clean everything.  To ensure the firing pin hole is clean, I have pipe cleaners.

After cleaning, I ensure all the sliding areas are fully oiled.  The cotter pin is is problematic to insert back into the BCG, but I'm getting better and quicker over time.

I'd like to hear from other shooters the pros and cons of just soaking versus disassembly.

Lew

Every once in awhile a BCG needs a strip clean. But not every time, imo. And I shoot suppressed, which is dirty shooting, even with adjusted gas.

I pretty much follow this. Regarding the firing pin retainer pin, I have found the Colt ones (Brownells) to not be nearly as stiff when pinching which greatly eases their insertion through and through. Went through that bs 3 days ago doing it all short of grinding. Grabbed one of the Colts and slid it right in without even a twist.

I soak mine periodically in Motorcraft carburetor cleaner, it loosens all carbon. I do completely disassemble to remove residue and oil
As far as the firing pin retainers, they are not all created equal. Colt and a few others have pins with tapered ends, some others’ are simply square cut.
Order a few retainers with the beveled tips

I don't clean things till they start getting other things dirty these days.
FWIW gunshot residue* is easily cleaned out with dawn and water, no need for soaking in oil of anything, good soak, dry it off, then some oil and get everything good with an oily AP brush, even then that would be FAR and few between.
I mostly just blop some oil on the BCG, and wipe it around with a paper towel

Over cleaning is bad for parts. People go WAY overboard.

*Which is what people always call carbon.  It's not, it's a mix of carbon in the form of graphite, and other left over junk from burning powder and oil that mixes together. It's pretty soft. It's why when people say "____ melts carbon" it's funny when you google the melting point of carbon.

Tip of a bullet works to remove the cotter pin also.

As far as cleaning. I usually just remove the bolt and firing pin, wipe everything down to get most of the carbon off then oil and put back together. Every 200rds or so.

After every range session, I just tear things down and throw everything in the ultrasonic. Comes out as clean as or cleaner than it was from the factory.

I then lube with Lubriplate 130A and everything is ready for the next range trip!.

I've never puller the extractor / ejector for the sole purpose of cleaning but have replaced. I do a basic field strip of the remainder and clean/lube after each session unless it was a test using few rounds, wtc. I lube liberally but not stupidly imo. If I'm shooting a bunch I'll moderately relube every 150-200 rounds or so.

I do some cleaning prior to putting it into the ultrasonic. I use a dental pick and some Boretech carbon killer. I just scrape the inside of the bcg so the carbon build up knocks out and soak it in some carbon killer. I scrape it a couple more time until a lot of carbon falls out. Then I put it into the ultra sonic. Comes out really clean afterwards.

The extractor comes off the bolt very easily, the ejector is a different story.  That roll pin is tight & I think is only intended to be used once.

Most of my shooting lately has been done with a nitrided tool craft. The shmoo just wipes right off, dont even need a cleaner. Using Chrrybalmz grease which I think contributes to the easy cleanup. Instead of the fouling getting baked onto the part most of it is suspended in the grease. I have an ultrasonic but dont even bother. Plus I also wondered about ultrasonic stripped all the oil out of the metal, lets say inside a bolt. I worry about corrosion forming inside the bolt perhaps where the firing pin channel is. I cleaned my MKiv Ruger in the ultrasonic after a ton of suppressed shooting and while it did a good job I was paranoid that rust was going to develop eventually in some obscure location. Maybe someone can ease my mind.

OP every time I fire my stick when I'm done at the end of a day, or end of a training week(s)/block, I will completely break down my stick and clean it to include the guts of the BCG.  It's simple, easy and it just works.