I feel your pain regarding painting the ceiling with flat paint.
I just finished Friday.
What a PITA.
2 gallons of Benjamin Moore 18% Kodak grey, dead flat.
It actually looks fine now unless there's a bright light shining parallel to the ceiling.
Initially I thought I had a disaster on my hands.
If I may, one tip and one caveat on painting can light trims.
My metal 4 trims had white rings and black baffles.
I painted the rings to match the ceiling.
Initially I tried doing it with my 40+ plus year old naked eyes.
I set up my lighted, 5x magnified hobby lamp. What a life saver.
I used a small foam brush.
Be very careful handling the painted trims as a stray fingernail will scratch the new paint and require touchup.
The end effect is very nice and IMO worth the effort.
Hey what's one more extra effort after about 300 of them?