Most Thursdays, yes. The age range was roughly 21-35. We all liked the 3 day weekend enough to do it regularly but I agree that physically it probably wasn't the healthiest of choices.

Interestingly enough, on slower weeks even when we could have gotten all our work done during the week we would end up doing a hack night. We had gotten so used to the habit that we would find ourselves procrastinating during the week so that there was work left for Thursday night.