I've been converting better than Mark's advertised rate. Everybody's mileage varies, but I'm happy. (Edit: And payments have been consistent.)

As for the original question -- I choose sponsors on reputation just as much as their payouts and conversions. So I spend relatively little time on tracking because I trust the payments to be there on or around schedule. I'll check a couple times a month since most of my sponsors are direct depositing, but otherwise I'm not going to waste my time over a few days delay, or to make sure it's there on a specific day, and certainly not over $30.

But I could see a small affiliate wanting to collect if they don't generate many sales (or if they plan to move on). Every last dollar probably means more to them.