The Obligation To Visit One's Rebbi On The Regel

The gemara in Rosh Hashana says that one is obligated to visit one's Rebbi on Yom Tov. There is a difference of opinion as to whether this applies nowadays after the destruction of the Beis Hamikdash. The Noda Biyehuda famously claims that it doesn't. Why not? Because we can only visit our Rabbeim three times a year if we are also visiting the Beis Hamikdash. If there is no Beis Hamikdash, it is not proper to give a Rebbi more kavod than Hashem.
We see that the Nodah Biyehuda learns that the mitzva of visiting one's Rebbi is related to the regalim and since there is no aliya la-regel there is also no mitzva of visiting one's Rebbe.

This understanding seems to fly in the face of the gemara. The source for the obligation is the husband of the Isha Hashunamis saying "Why are you going to the Rebbi today - it is neither Rosh Chodesh nor Shabbos". From here we see that normally one visits one's Rebbi on the regel. All of the meforshim wonder - how does the gemara prove that there is a mitzva to visit on the regel when the pasuk says that she would normally visit on Rosh Chodesh or Shabbos??

There are many explanations. One is that it depends on one's proximity to the Rebbi. The closer one lives the greater the frequency of the visits. Only those who live the most distantly are obligated to come only on the regel. There are numerous other explanations. [There is a shiur here. Pilei Plaos.] The common denominator of all of the explanations is that the obligation does not depend on the "shem regel" as the Noda Biyehuda understood.
Vi-tzareech iyun....

[Based on the Marbeh Zikaron Simman 47]

לרפורת שרה חאנטשה בת אהבה נחמה בתוך שח"י