I tend to switch it on first thing, and sometimes its left on allday as i come back to it in between housework etc..then it goes offuntil at bedtime, but if i'm going out for the whole day then i'll turn it all off.
Mines only put on to check my emails....to chat with a few friends and to add to commi i hardly ever use it Lol and it is always turned off when not in use.
Apparently it is better to leave a computer running all day than to switch on and off so mine is on all day (well i need it for my writing and genealogy work plus all my cousins , fam and friends write e mails regularly , my in box needs clearing every day cos it gets too full to quickly )