Tubes at idle

They do not, although their life shortens by idle hours as well.
It's definitely no go if you want to leave tube electronics on all the time especially when you leave your dwelling.
Tubes worm up substantially faster than semiconductors and therefore require only 5m of worm-up time before you start playing music. Than you need to idle them for another 5...10m of 'cool off' before turning off. Good quality 12AX7 pre tubes will serve you good decade with no problems.

08-21-14: Czarivey
They do not, although their life shortens by idle hours as well.

Czarivey, did you read my post earlier in the thread? If so, what is the basis for your statement that "they do not," which I presume refers to the question in the OP as to whether or not preamp tubes "get consumed at idle as fast as they do with music going through them?"

Regards,
-- Al

Good point Larryi, warmer internal temperatures means shorter component life.

Regarding tube amp care, I've used a 1960 Fender Deluxe tube guitar amp for maybe 50 years with varying degrees of on and offness and it works perfectly. Changed the tubes a few times over the years...but still. Also used dozens of other tube amps that were dragged everywhere for decades, dropped from loading ramps (thank you Anvil case), and otherwise abused...almost no issues. I have "soft start" features in my hifi rig in the power conditioner, preamp, and tube power amp, which I think provides all the mollycoddling and pampering the damn things deserve. Off when I'm not around, on when I am. I suggest people turn things off when not around just to keep from being wasteful boneheads or, if you do subscribe to the "leave it on" school of thought, don't admit it.