Leave tube amps always on?


Mark, the owner of Linear Tube Audio, suggested I leave my tube amps on all the time 24/7 if im listenting every day, and to turn them off if not using for a period of time, a few days or for example we go away.  His reasoning was that it uses considerable more energy to turn on/off on a regular basis. 

Do others agree?  Kinda risky since these NOS Mullard tubes ain't cheap and will soon be gone forever.   
aj523
If you really want to know how to treat Berning designed gear you should talk to the man himself. Turn off when not in use I say.
I use a tube preamp in my main system,and I don’t feel comfortable leaving it on if I have to run to the store. I’m a no vote on that one.
@audition_audio

Yes I thought I made that clear. Thats the suggestion from the designers themselves given the power surge in turning on and off multiple times. My healthy skepticism is questioning that. 
I just can't get myself to leave my tubed integrated on all the time, even though a tech suggested I do it.  It just doesn't sit right for this virtuous, right-thinking guy.  To be honest, if it does indeed shorten tube life, so be it.  It'll give me an opportunity to try out a different brand or model of tubes.