I "graduated" from twice a week to every two weeks once upon a time, and it finally felt appropriate because I was no longer in constant crisis. We moved along to once a month, and it was a good pace for us.

If you're having to go a month in between meetings because of logistics, I'd try to find someone else. IMO you just spend so much time trying to catch up that it's hard to get back into the rhythm and make progress in 50 mins.