When do you turn off the tubes?

Mine are on most of the time. I was told it was start up that caused most issues and a larger percentage of tube wear? 
I have a tube DAC and Pre with SS amp. 

Everything gets shut down if I take a break of more than an hour or so, or if I leave the house.

I’m in same camp

Shut down when not listening. Never leave on when not home. Simple. 

Many tube amps have a stand-by mode in which the output tubes are off but the amp is still warm. My Cary amp have this. When I'm home and know I will be listening that day they stay in standby. When I leave the house or go to bed, everything gets turned off.
I once saw my tube preamp go up in smoke while it was just idling.

I usually shut the amps off each time I am done listening.  Whenever I leave them on thinking I am going to go back to listening, my day usually changes so I can't.  If I turn them off, the odds of being able to listen more dramatically increases.  And, these things get hot-- including heating up the room when you have 8 kt120's per amp x 2, a couple of m8080's and a 6922 in the preamp, and the Sophia's in the CD power supply.  24 tubes total when everything is on-- that's too much electricity to waste if it's not in use.  And, finally, I have seen a tube fail-- right in my amp-- spectacular but scary.  I want to be around if/when that happens.