It turns out that exercism is an interesting illustration of a classic social-software platform: scaling.
The mechanics of exercism work like this: you submit your first exercise solution. Then you wait for feedback, and iterate. Once you’re satisfied with your solution, you can mark the exercise finished, and once you’ve marked a solution finished, you can start giving feedback to others on that solution.
If you’ve submitted a solution to an exercise, you can start another one in that language, even if you’re still iterating on the first one. This makes a lot of sense, because it turns out that you may be waiting a while for feedback. Essentially, there’s no barrier to joining the site and starting to do exercises, but because you need to have completed an exercise (possibly iterating three, six, even ten times on it) before you can start critiquing others, every exercise is almost guaranteed to have a much higher number of programmers submitting solutions than programmers reading and critiquing.
This can get pretty frustrating for a beginner. I sat on my first Ruby exercise for almost a week with no feedback until I got some. I iterated, and waited another four days until I got a “looks good” which I took as enough reason to mark it completed. (My submission for the next exercise has been sitting for six days without feedback.) I have three Coffeescript exercises waiting for critique, and one each of Ruby and Coffeescript waiting for me to start working on solutions.
The only way around this is for those of us who’ve finished any exercises at all to provide as much feedback as we can to others, and try to increase the pool of readers that way. I’m making an effort to provide as much feedback as I can to others working on that exercise, but probably what I’m doing is creating more work for whoever has completed the next exercise. The Ruby community is clearly larger than Coffeescript - whenever I look there seem to be around 70 active Ruby solutions waiting for feedback, but often there aren’t any Coffeescript solutions. So if I want others to be reading my Coffeescript, I need to be critiquing theirs…
ETA: And after I hit publish, I look at Twitter and see they’re aware of the problem.