That which it says in the Gemorah (Rosh Hashana 16b) that one has a obligation of "kabbalos pnei rabo" (to go see ones rebbe) on holidays - when is the obligation? Is there an obligation every day, or just once during the holiday? If it's only once is it specifically on Yom Tov itself or even on Chol HaMoed?
Certainly if the obligation is only one day, there would be a mitzvah every time he goes to see his rebbe. However, when is the actual obligation -- on yom tov, chol hamoed, or either one (or perhaps every day)?
(I will leave it to the learned olam here to fill in the sources that I have left out in the question as time does not permit at the moment to start looking. As well to make any changes in the question to enhance clarity.)