our individual experiences are greatly different. I'm right next door to you in NJ, an hour train ride. I have a daughter now in 2nd grade, a son in public pre-k (special needs with autism), and a son in private pre-k. all three kids have absolutely learned a ton from pre-k. im always surprised at the things they know and talk about that i know they obviously learned there since i never taught it to them. both the public and private are very much in lined with your "its insect unit time" blurb above from my experience. to my children it has really kept them engaged.

before i put my first kid into pre-k i said to my wife "well i don't care what they learn, i just want them to go and have fun and socialize" and she was the opposite and argued we should find a place that also emphasizes "kindergarten readiness" (whatever that is). as things would have it, she won. it was hard to argue against it since my parents didn't send me to pre-k or anything and i wasn't accepted into kindergarten my first go at it.