3 out of 72 is too big a margin for trust.
I would prefer a weekly 12 hour jam with limits better enforced? DTJ36 is only monthly.
I tried trijam once. Left it to the last minute, and had some doodles ready so probably only deserved about 2 hours of coding time. Thinking of something achievable in that time, takes too long to plan. As I recall the jam ended before I expected, but the amount of rubbish that would be submitted if the 3 hour limit was strictly enforced makes me suspect people are not entirely "accurate" with themselves.