[Amps] General question on filament life

[Gary Myers]

 Anyone have a feel for what life one might get out of a set of
 tubes if they left it on for say 12 hours a day most every day?
 Is this "better" than cycling power say 3 times each day ... I
 realize these are just "general" numbers... but would like to
 get some thought from the educated. It has been stated that
 cycling it is not good - but without details of what excessive
 is this is somewhat lacking in true info. Tom ('JI) had said
 that filaments are rarely the problem... is there any other
 downside to just leaving it on? [The amp in particular would be
 either using 3CX800's or 4CX800's - Titan vs. Acom2000A]

 thanks for your considerate comments.

 Gary
 K9RX