My laptop is a typical Samsung laptop with Windows 10 installed. Usually it turns off automatically when it is idle for about 15 minutes. I know that if a laptop turns off in the midst of a factory reset, its going to cause a hell lot of problems. So I'm wondering... Will a laptop turn off automatically when undergoing a factory reset?

Yes, if it needs to.

It usually won't shut down. However, it will most likely say, new... installed, restart needed to use program or some comment like that. I get notes from HP on my Windows 10.