For me, this one's a toss up. We had a blast during those late-night play rehearsals. Most of us went to school all day, had jobs after school, then had to be back at rehearsal that evening. We'd get out about 11pm, then had to be back up for school the next day. And yes, we did our homework too! (At least most of us did!)
Same for Valhalla rehearsals. Especially at Christmas, when we would perform 4-5 nights a week. School, then work, then rehearsal, then performance. Every Christmas season still brings up those memories.
Could I keep up with that pace now? No friggin' way! At least not without some pharmaceutical assistance...