Mark them at the house, sleeve goes into recycle bin and balls in pocket on bag. Eventually they will make it into the cup.

I also, keep the new ones in the sleeve and the scuffed ones loose in the bag for practice rounds

I keep my yellow Pro V1s in the sleeve until I use them. A used golf ball stays in the ball pocket.

I buy multiple dozens at a time, so I empty all the 1s first and keep everything else in the sleeves out of the bag.

I am a bit of both. Will keep 4-6 loose balls and a fresh sleeve in the bag at the start of each round.

Alex,
You've exposed a specific form of OCD!!
Suspect I fall into the "Repressed" category as they stay in the sleeves (pre-marked with purple Sharpie) in the bag.
At the start of the round, all 4 sleeves will contain 3 yellow AVX's while "odds", "pre-used" and "found/recycled" are loose in the ball pocket.
If I'm off piste (ie somewhere I've not played before) there may be a "Just-in-Case" marked up sleeve in with the waterproofs...
JT
PS If I empty a sleeve, it comes home with me for recycling.

I like to get them out of the sleeve and mark them ready for competition.

I keep 1 sleeve and 6 loose, and rotate a new sleeve in when I get down to 6 balls. Madgolfer hitemstraight

Used balls go in the pouch but I always have two brand new sleeves in the bag. Nothing like opening a new pack before you tee off... and slicing it OB.