Another option is to determine when you want to play and set that regularly and in advance. It's a lot easier for everyone to be available on every Wednesday night because they know that time is already committed.

Most games I’ve played have had 3 or 4 players, which is about perfect for most systems. The one time we only had 2 players, we both rolled up 2 characters each and played them simultaneously. It was actually really fun!

One thing about this is it assumes the schedule is made like on the fly. The group I used to play with played every saturday afternoon. It was like a club. You only join if you can make it. They rotated games/runners every so often and I got them to rotate every week so that a particular game would be once a month so I could keep doing it for awhile.

Lol. My current party isn't (it's just two people), but my previous party definitely was (13 people).

This is why you should play Shadowdark.