What to do about students who ask for help too often? For my writing courses, about 5% of students will come to me prior to deadlines asking for help with their paper. I see no problem advising students, as I often similarly came for help when I was an undergraduate. Recently, though, I found an increase in students who apparently just want to abuse this:


Students will bring me some plagiarized work, showing it to me early, as a sort of test if I will notice. It seems difficult to punish plagiarism when the paper is not yet submitted.
Students will bring in papers again and again, with little changes put in at each stage, hoping their minimal effort each time will be sufficient to reach their goal of a "D".


I've tried stopping students, but then they are angry when they see the "F" that they hoped I would help them get away from. While most of these students are probably just incredibly lazy, there is a chance that some among them are genuinely trying to improve, but just struggling a great deal, and I can't see it.

How might I go about blocking such abuses?
Here is one strategy:


Specify the level of changes the student needs to make before they can come back again.  
Request that the student shows you what changes have been made by comparing the old and new versions of the assignment.  
If student has failed to reach the level suggested or fails to show you the differences, simply tell them to go away until they have made the requested changes. Simply state that your previous comments still apply.


Adding a time delay between when they ask and when you give feedback or when you give feedback and when they can come again might also help.