Time blocks at a local 24 hour fitness center:

01:00 - 06:00 : NEET hour, if you go now you'll probably be the only one there. Dangerous if you want to lift, no one there to help if there's an accident.

07:00 - 12:00 : Pensioner hour, mostly old ladies walking on the treadmill or old men clogging up the equipment taking 30 minutes in between reps. Everyone is friendly and polite, but it's easy to become impatient. I can't recommend it to amateurs.

11:00 - 15:00 : Treadmill grandmas start to clear out and head to Cracker Barrel or Bob Evans for the early bird special. Second-least busy block, good time to go.

16:00 - 19:00 : Fitness mom hour, mostly young professionals in their late 20s to early 50s stopping in on their way home from work. A lot of fit, handsome dads around, if you're into that kind of thing.

20:00 - 0:00 : "youths", highschool sports players, dudebros, assorted miscreants. People screaming, slamming weights. If they play music at your gym this is when the playlist will switch from inoffensive and easily ignored top 40s to rap or nu-metal. Avoid.