Between freshman and junior year, I ditched maybe 10-12 classes total. First half of senior year, usually 1 class per day. I rotated them so I never ditched the same class twice in a week. Last half of senior year it was a serious case of senioritis. I ditched at least half, almost always the early morning and late afternoon classes. I'd get into school after 2 or 3 hours sleep and head to the senior lounge for a 2 hour nap. Refreshed, I'd tackle the classes from 10:00 to around 12:30 and then get bored and skip the last two.