I think it depends on a few factors. One how much I like the photo, how important it is to me. The other how difficult it is to print. One is related to the other. Generally with a decent negative (one reasonably easy to print) I'll do a work print and evaluate it. Usually with one or two test strips and one or two full size enlargements I'll arrive at a decent work print. From there I'll evaluate what needs to be done and I'll arrive at a print I'm happy with with a few more attempts.

For more difficult to print negatives of prints I feel important I'll work as Don mentioned above. I'll do the best I can and go back to it a few months later. Unfortunately my favorite negative is under exposed by at least a stop and needs a lot of burning and dodging. I've gotten to the point where it is decent but still needs some improvement.