This is a mighty good idea. Especially for those not in the same timezones.
I've seen it happen to good games that threads ran away with the plot so fast that 1. a part of the players (strangely it mostly seems to happen with those living in Europe) don't get a change to post and 2. the game burns out too fast. Happily the rules here seem to work so this doesn't happen, which doesn't say that a slowing of 'game time' wouldn't help in keeping it so.