Back in 2007 I wrote a Matlab package for estimating regime switching models. I was just starting to learn to code and this project was my way of doing it. After publishing it in FEX (Matlab file exchange site), I got so many repeated questions on my email that eventually I realized it would be easier to write a manual for people to read. Some time and effort would be spend writing it, but less time replying to repeated questions on my email.
This manual about the code became, by far, my most cited paper in Google Scholar.