No. What dipshit would leave the entire zone (either by warping or running back to entrance, just to leave; afk for five minutes and come back.) I'd rather afk in Dynamis for ten minutes than to do all that running back and forth for minimal reward. I also see that if a zone is full; then some people who don't like competetion would leave and wait until afterwards to re-enter. Leaving more mobs for those that stay behind.

You would still only get 2 hours a day, you could just split up the time. I see no way to exploit it.