There are two issues I need to bring to your attention:

• You appear to be vastly underestimating what kind of time and effort goes into providing feedback that is helpful to students. Twice today students have marked your feedback as unhelpful, so that your feedback could be disregarded (the system otherwise would regard their work as having received feedback, thus dropping its position in the list and reducing its chances of getting further feedback from others).

• Your choice to assign a full redo of the lesson material here is really off base. While you are correct that they are not executing their marks with as much confidence as they require, it is not nearly to the degree that would require a complete redo of the entire lesson. If that's not what you intended to assign, then it certainly wasn't clear. I will say that linking to Scylla's videos is certainly a good thing to do, so I'm glad you're referring to other material, but unfortunately you simply cannot reasonably assign someone a full redo of the lesson without really explaining why. While I certainly don't expect you to know exactly how I would handle a situation, for future reference, in a situation like this I'd simply stress that the student should make a point to execute their marks with full confidence, free from any hesitation or concerns of accuracy, as they move into the box challenge. After all, the box challenge has them drawing 3000 additional freehand lines, so they're going to have ample opportunity to correct that issue.

Not everyone is in a position to invest the kind of time that useful feedback really demands, but that simply means that those individuals who cannot should, instead of attempting to provide feedback that falls short, leave it to someone else who does have more time to offer. If you do have plenty of time but are simply unsure of how to provide feedback that provides a clear assessment of what the student did right, what they did wrong, and what their next steps should be, then I strongly recommend that you take a look at the unofficial critique guides Elodin's created for Lesson 1, the Box Challenge and Lesson 2. They are effectively checklists that allow you to go through every major section and provide useful feedback for both.