Both my earlier campaign arcs have taken between 14-16 games to play out. For a group that meets roughly bi-weekly that meant the game stretched across several months. But over the last 18 months (since my last campaign ended) the regularity with which our group meets has fallen to a new low. Life, unfortunately, has a habit of getting in the way of a regular schedule. Nobody is 100% happy with the current situation but we all accept the inevitability of it and are trying to maintain games around our constantly shifting lives.
The problem with a very irregular pattern of games, with breaks between sessions of anything up to 6 weeks some times, is maintaining plot cohesion. By the time we have completed a side quest for instance we have forgotten who it was hired us in the first place. As a group we try to overcome this with comprehensive notes between games and recap sessions before we start play. But its not the same as meeting on a weekly basis and following a story through from beginning to end over just a few weeks.
One possible solution that I'm now toying with is a shorter, simpler campaign arc. It would mean making some radical cuts in the story I have already written but it might make for a tighter adventure that will stand up to the fragmented nature of our gaming sessions. A story arc that could be covered in say just 6-8 sessions could still last our group for months and stands more chance of being understood by infrequent players. The other advantage is that a tighter story might actually be better than one that rambles on for ages. In my last campaign my players had a long journey to their objective which on paper only last three games but in reality went on for nearly three months.
So I've broken out the scalpel and I'm trimming the fat. Size, as they say, isn't everything.