1 game every 3 days is still 30 games assuming he has the best rating already. If you have a specific suggestion on how to promote activity wihtout it being abusive I'm all ears. If you have a way so that massing games won't be abusive, but very small activity will be very lightly penalised I'd be inclined to put that into rules.
point for every won game, but no more than 3 points per day.
edit:
well, maybe something like 'no more than 20 points per week' as people don't play every day
Edited 8/31/2015 14:36:43