If I am sewing something with a specialty or combination stitch I will leave it on all day if I need to get the project done so I don't have to re-program the stitch.
I would imagine that turning it off and on constantly can't be good for the light bulb.
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My newest Grandson, Caleb Austin, was born May 29th. I am now Grandma to 4 precious babies. I am so blessed!!!!