Thats a little too long, don't you think? School ends around three where I live and you play for five hours on school days? Maybe more? So 3+5= 8 o clock + homework + shower + dinner = bedtime probably...so...wheres the social life?
unless it interferes with your social life, school work, and job(if you have one), then your fine to play as much as you want, granted you keep those three things up to par.