Dean Jones says:

"Perhaps I can adjust the offer a bit:  How about EIGHT PER ACADEMIC YEAR?"

Your response:

1.  That is better...I think that FOUR per year is the right number of undergraduate independent study-type projects to supervise.

2.  That is better...I think that FIVE per year is the right number of undergraduate independent study-type projects to supervise.

3. That is better...I still think that SIX per year is the right number of undergraduate independent study-type projects to supervise.