To be completely honest, I would not recommend doing 20 Time next year. The concept is good in theory, but there were some major issues with the execution. The majority of the kids barely did anything regarding their projects, so I'm not sure it's fair to do something in favor of the minority in this case.
I enjoyed the blogging. Not every week, but the every two weeks was nice. It helped keep everything on track. I know there were a few times where I wouldn't have done anything regarding my project had I not had to blog about it in the coming weeks.
At the very end of our projects we began checking in with the class and giving minute long talks about how our project is going, what we've been doing with it, etc. I think if that had been started earlier in the year it would've been very beneficial for a lot of students. You're much more motivated to do something if you have to stand up in front of an audience and explain your results.
All in all, 20 Time is good in theory, but not in reality. I would suggest trying something new next year, but it was a fun experiment!