I think veterinary medicine is on top of the list. We have a lot of lectures, practical classes etc. although the exact amount varies with the years (last week I had 33 hours of contact time although other weeks I have fewer hours). On top of learning anatomy, diseases, husbandry, nutrition, clinical skills for multiple species we have to complete (unpaid) placements during our holidays and log our learning outcomes and fill in a journal etc (on one placement I worked from 5am to 6pm!).
I also live with engineers and think they have a very high workload too.