rule of thumb: how long do you leave a tube preamp on versus turning it off then back on?

Thanks to everyone for their thoughtful answers. The general gist of things as I summarize your comments in my mind is that common sense should prevail and to turn the preamp off when I'm done for the day, clearly stop worrying about tube life and enjoy the system. The REF 10 does have a 12 volt trigger turn on and off feature as do my Parasound JC1+ amps. This may somehow be audiophile heresy to make use of such a convenient feature, but I love it and with the REF 10 start up mute and delay sequence it seems to work very well.
 I was also asked how I like the new REF 10. I absolutely love it, its less" tubey" than I expected, strikes a great balance between the classic tube and SS sound (so did my Rogue RP7), imaging and depth are great, and I've never had a preamp that didn't seem to change the sound as I changed the volume. I literally get lost as to where I am with the volume level. I will notice that sometimes I am listening at a relatively low or high level without choosing the level numerically, just enjoying the music.
Finally, like many of us, I wonder if I had this or that component would I enjoy my system more. At this point, I don't have any desire to try any other preamp, and that my friends is a wonderful feeling! I hope it lasts!!
Thanks again for the insights!

I have had the exact same thoughts as you, OP.  I read through the posts and didn't feel anyone actually addressed your question.  If I am hearing you correctly, this is the scenario.

You have had your stereo on for whatever amount of time listening and your family wants to watch a 1 hour show, so you have to decide.....do I leave everything on and go watch the show and then come back and hit play or do I power it all down and then power back up an hour later.  

Which is harder on the tubes, an hour of idle time or the power cycle?  

I understand the incentive for sound quality, but I too don't know which is harder on the tubes regarding their life.  

It seems that many electronic components in our lives are more stable when left on constantly vs repeated power cycles.  

Seems we are both over-thinking and should just leave it on for reasonable amounts of idle time.

Yes, thank you for reframing my exact question! I think no one may actually know the answer because there are too many variables for a "rule of thumb" guideline. Lots of well intentioned responses. I'm going to turn it on a little before or concurrent with my listening, and leave it on the rest of the day, turn it off when I head to bed. Done! I'm over it!! Thanks!

@wokeuptobose


Don’t know if this has been covered. But NEVER turn a piece of tube equipment off and back on quickly. This is one of the best way to cause problems with the equip. .
You having already owned tube amp, may have already known that. But just in case....

Thank you for reminding me! I have known that most damage to electronics is caused by the cycling of being turned on and off. I will be doing power cord and interconnect shootouts and I'll be sure to be careful not to cycle it on and off. I used to leave all my solid state gear on all the time, but a few years back we had a voltage surge and it damaged my Wadia 16, three TVs, two sound bars and several other electronic items. Now I'm careful about turning my system off each night. I did install a Leviton whole house surge protector at my panel and I do have everything but my SS monoblocks plugged into a Shunyata Hydra Delta 6 which theoretically has surge protection, but factory claims about "FULL" protection are unclear to me.