Back to preheating.
Bill made a good point about the thermal expansion/contraction noise of some fixture housings - good reason for warming up a fixture before house opens: the fixture housing has enough thermal mass to stay pretty warm while off for a scene or two.
The theory is that warming the filament before use can improve response and may extend lamp life; however, keeping the filament warm over an extended period wastes energy and potentiallly shortens lamp life. I wonder if anyone has thought of putting control of preheating into the console insteand of the dimmers - it might be useful if the cue before an conventional is used could automatically preheat the instrument.
Yes, I have run shows where I have preheat programmed in the console to carry through the whole show. It seems like most lamp failures occur at cold inrush. I do lamp check before opening the house and keep them warm until the show ends. I only have anecdotal evidence, but I have not had any mid show lamp failures since I started doing this.