This would actually be a longer game than normal (4 years instead of 2,5).
Len, you should check out the revised rules on turn timing. You can't really 'miss' a turn anymore because there is no turn deadline. If you play in a 14-day game and you send in after 20 days, you get 20/14 of your production and move your target processing date 6 days. If you just want to be able to send in after three weeks or four weeks every once in a while, you can now play the regular 14-day games and do so.
(of course, if your opponents do send in every 14 days they will get a double turn on you sooner or later if you do, but at least the computer won't start making turns for you after 14 days anymore)
That has always been true Mickey, however, you only get up to 100% increase. If you wait 29 days for instance, you get 28/14, not 29/14.