For me a majority of my equipment is either off or on standby. The only things that would remain on 24/7 is the gear that doesnt have a power switch. To me if it doesnt have a switch then it was designed to be on all the time. Gear I have/had like this a McCormack TLC-1 Deluxe, various Audio Alchemy DTIs and DDEs, my isolation transformers (Tice Audio/Topaz). Ever since I got a Kill-A-Watt and found out what some of my equipment draws either at idle or with a load I wont leave my gear on all the time. Some amps I have draw 100 watts to 300 watts at idle. I know this isnt much but it can add up to the electric bill.
Do you leave your components on 24/7?
Lately I've been leaving my components on all the time, on the assumption that a) they'll be ready when I want to listen, and b) the on/off cycle ages the equipment (tubes, anyway) faster than leaving everything on. Is the latter a reasonable assumption?