Two weeks into my free community, I noticed the comments do more than my posts. Members give each other feedback, and that's how they finish things. So I'm thinking on testing a 7-day challenge: say where you're stuck, pick one small thing, show it, get feedback, finish it by day 7. My concern: does a challenge bring people who stay, or people who leave on day 8? Have you run or joined one? What happened after it ended?