Look at the killer game, it lasted all summer long
It started in August, so no.
If you want to play a game that only lasts a week, there's Mafia. All forum games don't need to adhere to that timeline.
The "marathon" idea might work though, up to the host of course.
Quote from name:Tuxedo-Templar
Also (and this could apply to TKG as well), you could allow "default" actions for each player to define and revise at any time. These are actions that kick in when they do not submit explicit turn actions for any given round. They're like auto-pilot instructions, in other words.
I've addressed this in TKG, and think it is a bad idea. Someone who only ever submits one turn, just to define "auto-pilot actions," shouldn't be able to kill off active players. Actively playing should give you a distinct advantage over someone who hasn't logged in for a week.
Someone decides their time is better spent doing something besides forum games, and before they go absent they set "auto-pilot" instructions to try to influence the game after they've gone idle. Since they no longer have a stake in the game, their actions are generally not conducive to the enjoyment of the remaining players.
In TKG, there were 3 people who attempted to turn in actions that would "repeat" on every subsequent turn, putting them on "auto-pilot" so to speak. All 3 involved standing idly in a room and killing anyone that entered.
If you're going to "marathon" 3 turns per day, someone submitting all 3 at the same time should be alright, since they would still need to get on once a day to do so. However, not needing to be active at all defeats the entire point of even playing, and isn't fair to those who make a point of actively participating.