Leaving tube amps on.

This is a question I had for a long time. I know it’s not a good idea to leave tube amps on all the time because of tube life and safety reasons. But sometimes I don’t have the opportunity to listen to my system / music for hours at time at one sitting. Sometimes I can only listen to it 45 min - a few hours at a time during the day / night. So my question is would it be better to leave the amps on all day / evening and listen when I can or turn them on / off every time I listen even if is only  45 min at a clip. But to just clarify when I don’t intend to listen that day/ night they will be off. Does turning the amps on / off throughout the day / night do more harm than leaving them on ? Tube life , wear and tear on amps etc. btw I have the Audio Research Ref 750s. Ea amp has 18 KT150 , 6550WE , 6H30.