Problem about that though is that not everybody who participates in a CG has hours worth of free time on a daily basis to participate due to work or life getting in the way, most of the time it's those who have hours worth of time to spend that get a high participation %. If anything these modules should be a side-reward as part of some system that can give out rewards to those who have utilized or shown skill rather than the ammount of time invested, but I'm not sure how such a system could be implemented exactly. Regardless I think 50% is more agreeable, 25% is too low and 75% is maybe too high but 50% is a good half-way point atleast for the time being.