I usually leave my machine on for whatever duration I'm in the sewing room. If I know I'm just popping out for a short bit -- changing laundry; lunch; etc. -- I'll leave it on as well. If I know there's a likelihood I won't get back in there for hours/days I usually remember to turn off the machine (but not always). Following those practices, one of the lights only recently blew in my Viking and it's about 10 years old. I don't know that the lights or machine draw enough power for it to be a significant cost savings to turn it on/off every few minutes. Then again, it might.