I turn my tube integrated and CDP/DAC on and set the kitchen timer for 25 minutes and that's when I begin listening. It sounds best after an hour. My CDP requires this warm up, not just the tube amp. I think leaving your gear on 24/7/365 is nuts but that's probably because I can't do it with my amp. I would never purchase used gear from someone if I found out it was on 24/7/365.
How long it take before your system/amps sound
...the best. My system sounds the best after 12 hours of playing. I didn't realize this until I inadvertently left my system on overnight. I was surprised how much better it sounded compared having the system on for an hour or two. I have tube DAC and amps, which probably are the reason for long warm up. His really surprised me.