I would suggest that any buffet (with the possible exception of Wynn and Bellagio) is simply not worth waiting for at all.
I see your point, but IMHO it's part of the Vegas experience to go to a buffet (once per trip is plenty). It's just part of the sense of excess, giving in to temptation, etc. Playing slots isn't cost-effective, either, but hey, you're in Vegas. (I'm speaking as a real high roller who puts $5 in a 25-cent machine each trip
)