Unless I am rebuilding itI leave it on as I am crunchingbut will have to see how much the elertric is, as since the move I have only just had a estimated bill as the freezer is in front of the meeterand cannot read it till we get a under counter freezer for the kitchen.
I switch it off when leaving for work, otherwise as long as I am in it's on. Since it is a laptop keeping it connected to the mains all the time results in battery wear.