There's not actually figure of attendance, for me I haven’t gone to school for 3 weeks, only go for math. Just because my Bio/Chem and physics teachers are horrible and only rewrite what’s on the text book on the board.
I stay home have wake up at 8ish then have five, three hour study session e.g. 9 to 12, 12 to 3. If I go to school I lose that 6 hours plus can sleep in for extra one hour. Some times school makes you grouchy and tired when you come home your Cbbs to study
But if your attendance drops below the school requirement they will ring your parents, so don't worry stay home if its more productive for you.