I do not think that the longer they stay with OW the better the chances of them staying together. I think they all see the light, and want out of the relationship. Some will leave and some are too proud to admit they made a mistake. Some will leave to be on their own, and others will not leave until they have someone to go to. Like their wife.
I think that is what happened to me.
Bomb 1/06 D dismissed 11/07, attempt reconciliation. Premature. Divorce final October 31, 2008. OW looks like bad history. Over. Still hopeful. Baby steps. In R with my X.