Do you leave your components on 24/7?

I experimented with my modest SS system, left it on for couple of days and in another case didn't leave anything on.
Well, it didn't really sound good cold. However, there was no or little difference in sound between being on for two days and being on for two/three hours. So I usually keep it on on weekends and turn it on on weekdays in the evening.
Another point might be that you don't want your equipment to be on and even plugged in when there is a storm. And one can never predict the weather.

I leave everything on standby that is solid state, but not the pure class A Threshold T-200 - it takes about 20 minutes to warm up and start to sound good. The outboard power supply of my Threshold DAC-2 runs extremely hot, but I leave it on anyway since the manual recommends it - and there is a noticeable difference after it's been on for about 72 hours.

Never. I turn everything off.

Yes, unless I'm going on vacation.

My gear seems to sound great after 20-30 minutes. This includes tube and solid state. None of my gear sounds bad enough so I can't enjoy it while it's warming up.