Most of our postal games have deadlines either one week or two weeks apart. All our current one-week games use the short deadlines because they're sports simulations that use real life stats (and real life sports produce stats every week, so our games run every week).
The rest of our games use two-week deadlines because we've found that's what most of our players want. If you're new to play-by-mail games it might be surprising, but more experienced players usually like longer deadlines. This is because they prefer to spend time thinking through their options for a while before they decide what to do. Games that involve lots of thinking and planning are usually the ones that work best by mail.
Another advantage of two-week deadlines is that with two weekends between each deadline the schedule fits around anything else you might be doing. If you haven't time for your turn one weekend then you can leave it to the next. Even so, many players like to have a turn every week, even with two-week deadlines, so the most popular solution is to play two different games with the deadlines in "opposite" weeks.
Other postal games use different deadlines. Many amateur run games often have deadlines of five or six weeks, which tends to restrict them to the most experienced and keenest players only (you'd better be serious about a game if you want to remember what you were doing last turn if it was six weeks ago). Many of the simpler football games use ten day deadlines, but most of these are games for kids and there isn't too much to think about.
The best and fastest professional GMs will turn games around the same day. This means the game reports will be back in the mail before the last post on the same day as the deadline. If the postal service is good then there's a reasonable chance you'll get your game report the following morning (or the same day if you play by email).
The best a semi-pro or amateur GM can hope to do is overnight turnaround, running games in the evenings and putting them back in the post the following morning. Given the need to keep up with the day job, most prefer to set deadlines at the weekend. This makes for much slower turnaround times (there being little or no postal service at the weekend) and makes weekly deadlines unworkable.
Using The Internet
Turnaround times should be much faster by email. Orders written online will normally will be delivered much more quickly (experienced postal players don't rely on next day delivery: you need to allow three days for first class post if you want to be sure your orders will arrive on time and almost never be late).
Game reports send by email should be delivered within minutes, even at weekends. This will also improve turnaround times, especially for weekend GMs.
For games that are designed to run on the net we'll offer deadlines of one or two weeks (there's a space on the startup form to say which you'd prefer, or you can sign up for "either" in which case we'll put you in whichever games starts first).
If you'd prefer something in between (10 days) or something even shorter, then let us know. We'll run whatever people want, provided there are enough players to make it work.