Guitar amp power on question

I have a variation on the oft asked power on question. I have an all tube guitar amp. It has a standby mode. My question is this - Am I better off turning all power off between playing sessions, or leaving main power on and in standby mode?

I like to play multiple times each day as my time permits. It may be for 10 minutes or more than an hour at a time, with as many as a few hours between playing. Worst case the amp will be on for 8-9 hours on a given day, and played only 2 of that. The remaining time on standby. Otherwise it will be powered up perhaps 8 times over that same time period, but for only 2 hours of play.

Thanks in advance.