Heh lol what a funny question...it's really your preference...it SHOULDN'T matter how long you leave it on, but obviously you'll be using electricity if you leave it on. Often times I just put my laptop on sleep so it uses very low energy. I can't imagine it uses that much at all at such times. You should really only HAVE to restart it when a program prompts you to, but you're bound to run into a glitch eventually if you just always leave it on.