When do you turn off the tubes?

Having had recent surgery and spending a lot of time at home, I was wondering how long a break from music do you feel you need to be taking before turning off your tube amplifier.I could leave it on all day even when not listening but that would be 12+hours/day.While my PrimaLuna Dialogue HP is gentle on tubes, the thought of retubing 8 KT150s is an expensive prospect.I usually turn the amplifier off if I am not going to listen for around 3 hours.What do other people do?

Since you are concerned with tube life then it seems what you really want to know is where is the break-even between leaving them on and turning them on. A lot of that depends on things like the way the tube circuit is designed. Only PrimaLuna knows that. Why not just call and ask them?
Interesting thought. 
I will try them.
Everything gets shut down if I take a break of more than an hour or so, or if I leave the house.
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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.