It would effect players with less time in the sense that they would not be able to participate in it nor get anything from it. Whether the monster spawns once every 2 seconds or once every 2 days doesn't matter if they both take the same effort to kill. You're just limiting the amount of people who could participate. You can scream that it takes more skill till your face turns blue but the skill is in actually... you know? fighting the monster. It takes no skill to claim something.

/ma "Stun" <stnpc> >.> my god that was always so hard to do in xi. Took mad skills to run around tabbing for monsters while not being able to leave my computer for an hour + waiting for a pop window. :3 Skilllzzzzz