How long do you leave your computer on for? Or, is it on all the time? And why?

I usually have my computer on for around 7-8 hours on weekdays and like 12 hours on weekends, especially for those downloads I learned some offices and places never turn their computers off, and computers are meant to be on for specific reasons(like updating and stuff), and that it's more taxing turning the computer on and off rather than just keeping it on. But to me, I'd rather have mine off when I'm sleeping.