Stanley,
The largest class I have ever had online was over 400. The lastest class I taught online was over 200 students. I typically provide comprehensive feedback on the first assignment to get them started on the right foot and include a few "snippets" of what they should do in the future. Then, when they make the same mistakes, I tell them to go watch/listen to the first assessment. Do you really need students to turn in 120 assignments each week that YOU grade? What about peer evaluation? Group evaluation? Thanks for your input.