Jcm,

I tend to agree with you, but some rebuy tables are sweeter than others. If there is a maniac at the table pushing every hand, I'm happy to keep rebuying, because I can accumulate more playing 45 minutes against that guy than I can playing an hour at a calmer table tomorrow.

Another thing to consider is the amount of money at the table (which of course has a lot to do with the presence of rebuy maniacs). At a juicy table, it's often worth two buyins to stick around, even if no one is playing especially badly.