well I had some study leave organised for months, the project was going well, and during the study leave a job came up. Now I wasn't looking, but something came up that was local (I live in the technology boondocks) which looked interesting. So I was already doing supervision and critical bugfixes only, although the team was growing, partly to temporarily replace me and partly because the project is successful. So I was on around 20 hours the first month of study leave, two on the second month, and I think in month three I will quietly fade away, just making sure that the main new guy understands the reasons for some of my more superficially insane design decisions.