I would say a twenty-four hour rule is the fairest and most applicable, but a safety component should be integrated. I am firmly of the belief that for the health of the game to continue, the character in question - if their player does not post in that time elapsed - becomes a non-player character for that turn under [@Hekazu]'s control. By this I mean that their character, based upon their alignment, behavior, personality, interests and so forth and the event itself at hand. Either they filter into the background for the scene until the player posts, or if in combat, performs the most reasonable action for them.

I say this because I often am away or on during unusual times. There is a chance that I cannot post even in a twenty-four hour period, unlikely as it is. I would rather trust the Dungeon Master to not place me in jeopardy and spend my turn doing something reasonable, rather than making anyone wait or making myself useless and performing no action, thus creating more problems for the party as a whole.