Weekly is about right. Many groups whose individual members have responsibilities that stop them attending so regularly are large enough that it's not the end of the world if there a few no shows each week to compensate.
I haven't played in some time. Used to play every week. Now we're shooting for once a month. It's a shame that it has to be so hard to cordinate 4 or 5 people's lives enough to do something just one time per month.