We have done it on smaller stuff, e.g. strikeouts, base hits, or pull-ups. It makes sense that it would work on the big stuff too.

By the way, the pull-up thing has been fantastic. In my whole life, I've never done more than three. My boys have done 20, 15, and 10, respectively. $20 for the first five, an additional $40 to do ten in a row, an additional $60 to to fifteen, etc. For years, anytime we passed a playground, they'd run over there and try to cash in.