Last Wake Window Puzzle

My baby’s sleep has been such a puzzle since the 4th sleep regression.

On a 2/2.25/2.25/2 schedule (last WW varies because I get panicked on overtired vs undertired…)

Before, he put himself to sleep at night. And is able to for 80% of his naps. Used to wake up 1 time a night. Now wakes up 2 and often has an EMW.

He is 6 months in 1 week and the last nap of the day ends up being 15-20 min but often puts us past 5pm.

Ever since he was a newborn he did better with a shorter last wake window. But at this point I can’t figure him out.

If the last nap is 15 min, I put him down 1.5 hours later and when he hits the crib he cries until I hold him, then he falls asleep almost instantly in my arms. If we have a day where he sleeps around 30 min for the last nap, if I put him down closer to 2 hr is in the crib messing around seemingly trying to put himself to sleep. And then he escalates when he can’t get himself there, and cries for help.

I feel like I have a timing issue vs a sleep training issue. Anyone have any tips?