Leave tube amps always on?

I still turn them off even if I know that I am going to listen later

I thought that David Berning was the sole designer of the LTA gear.  

I don't own LTA, so maybe that is a very special case. Can't speak to it.
In addition to fire hazard, tube life (both good points), my gear consumes over 100w when idle. I listen probably 2 hours a day, maximum, on average. This probably doesn't mean much, given the other factors, but at my electricity rates, the difference in energy use is $105 vs. $9. For decent tubes, that's the cost of about 2 tubes per year in energy savings. Over a few years, it would add up.

On the LTA website it mentions that they drive the tubes with 1/3 of the amount of current that typical tube amps use which is part of the recommendation.
Also many believe that tube life is shortened because of multiple power up / power down cycles. Consider the physics of a cycle- abrupt current and heat to a cold tube and tube glass, thermal expansion differences between materials- e.g. glass and different metals and pins that are expected to hold a mechanical vacuum to survive.  Running at temperature and maximum thermally expanded state for many hours then a rapid cool down / thermal shrink after power down.  This happens every power up / run/ and power down.  Thermally and mechanically stressful to the tube elements and glass.  

Most tubes do seem to fail at startup as opposed to failing gracefully while running- similar to an incandescent light bulb.

I would consider leaving them on with an LTA product and see how it goes.

"Tubes, generally speaking, are NOT like light bulbs, so they do not suffer nearly as much from the thermal shock of being turned on."      Actually; the cathode in a vacuum tube is heated by a refractory metal filament, generally tungsten, very much like a lightbulb’s.      Some cathodes (directly heated) are the filament. https://en.wikipedia.org/wiki/Hot_cathode      Even so; as much as I’ve spent on my NOS valves, persuading me to leave them on, 24/7, would be a difficult task.     Glad my Cary monoblocks have separate B+ switches, so I can give the electrons time to start their hot little dance.