Extra work and higher quality work could earn a higher grade. I could get away with letting students set their own goals, because I had taught each of them before and we all knew I wouldn't let them get off easy. The students who were unsuccessful were the same students who have always done poorly because they aren't responsible enough to turn in their work on time. As you have expressed, the results of these workshops are exciting. My students were enthusiastic and really enjoyed sharing their reading and writing with others.
Many students read and wrote much more, and much better than they had in past semesters.
The principal of the school complained to me, however. She wasn't concerned with student accountability. I couldn't believe it. But, I'm not teaching there any more. Reading the responses wasn't that much work for me, but responding to them in a meaningful way was.