I have been sewing for decades and can only remember replacing one light bulb. I leave my machines on (the one I am sewing on) for hours if I am not done sewing for the day.
It is plugged into a surge protector (it is a Bernina Artista computer/embroidery machine). We can see my machine from the open archway in the kitchen so it never gets left on overnight.
On my FW I do turn the light off if I am leaving the machine for more than 10 minutes to let it cool off. It does heat up the shield that is over it and since it is metal it gets quite hot. In the scheme of things I believe the light bulb does not cost that much considering the convenience of not having to turn it off and on all of the time.
This is all just my humble practice and opinion. Happy sewing!
I should note here that I did buy one of those irons that turns itself off if left more than 10 minutes without ironing. Some consider that a nuisance but I consider it a safety issue and it doesn't take long to heat back up.
Last edited by SewExtremeSeams; 03-18-2015 at 09:16 AM.