Do you have a baseline of preps that you tend to keep on hand? How do you inventory or prioritize it?

Yes.
We dont. It's our lifestyle.

Yes. I think of layers. First being edc and the stuff I carry all the time. Next is more expansive and has stuff in my truck to make life better. Then it’s home.

Really the priority is stuff you need to survive no matter what’s going on. So food in the pantry, water out of the sink, shelter, clothing.

Once you have that settled you just expand from there. Not rocket surgery really. Look at things you need every day. Think about how you would accomplish that task with your utilities shut off for an hour, a day, a week, a month. You already have redundancy in your life most likely so leverage that.

Say I want to get up right now and make rice. I have to heat water. To do that without prepped mindset I could use the microwave, stove, oven, bbq grill, make a fire in the fireplace or yard, or smoker. If I lost power I would still need to heat the water but some of those options are out. If I lost power and gas all those options are reduced to the bbq or fire In The yard. Or camping stove. Or propane torch in the shop.

That’s how I view prepping. Having the materials and ideas on hand to accomplish a task in changing circumstances

Start small, then expand.

"How do I get through..."
Tonight?
The next 72 hours?
The next week?
The next month?
The next year?
...However long I want to go?

EDC, defense, first aid, etc.
Gear to "camp out"
Gear to keep the house going for "x" days/months

Add financial in there as well.  If you lost your house to a fire, what would you do?  Can you buy the things you would want to make a catastrophe into an inconvenience?

I think of this in terms of categories, trying to solve everything to the 50% level or so before going too deep into one area.  That philosophy can be applied to a group prep as well- where you have the med guy go deep into his lane while others are assigned their own areas of expertise.  But again, I think a baseline of knowledge (more important than stuff) and stuff across the board is critical.

Categories to consider might be:

Water
Food
Medical
Defense
Comms
Tools
Trade
Travel
Misc

I like this, and although I've never actually thought about it, I did this also.
Think of all the events you want to be prepared for; snow storm, power outage, pandemic, self defense, social colapase, etc.
Then start with the most likely figure how your going to make it through the first period. "72 hours" is a good rule of thumb, but doesn't apply to everything. For example self defense. 72 doesn't apply. So I say phases.

Phase 1 of self defense is having your CCW, and a weapon, well for me it is, other it may be different. Phase 2 might be a reload on your person, it may be a reload in your car. It may be medical gear.

In other terms, phase 1 might be a stocked cubard of a week or 2 worth or normal food. Phase 2 might be dried goods.

I have thresholds for things like gas, long term storage food, batteries, propane, carb cleaner(& other mechanic related aerosol), spare parts for small engines, and some extra motor oil but that's about it.  TP we replace what we buy but only keep a few bulk packs on hand.  Same for everyday food items and frozen goods, replace what we use and try to buy during sales etc.

I do my best to have a full wood shed every fall.

I don't keep spreadsheets.