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
Two years ago I asked Kevin Deal, Upscale Audio at the RMAF show (Denver) should you leave an integrated amp on 24/7 or only when needed.  His expression and definitive answer was "Only on when you use it!"All my integrated amp's tubes still sound good today.  I just occasionally clean their pins.  :-)    
This roundtable is entering the "How many angels can dance on the head of a pin" phase.
@hilde45 


Thats what I was thinking. How many electrical engineers with qualified expertise have actually weighed in here other than maybe atmas-sphere. 
@vinylfun

Sorry I dont know Kevin Deal. Is he an engineer ? What audio manufacturer  is he or / work for?

Kevin Deal is the founder/chief of Upscale Audio. Though I am not 100% sure on this, I'm pretty confident he's the guy behind the PrimaLuna brand.