"Get Yourself a Rav"

Q: Does the concept of "Get Yourself a Rav" (Pirkei Avot 1:6, 16) mean that you must have one Rabbi for everything?
A: "Get Yourself a Rav" is not an obligation. It is not stated in the Rambam or the Shulchan Aruch that one is obligated to have a Rav but it is exalted advice. If a man has a Rabbi, the Rabbi can direct and guide him. He helps to exalt him in a spiritual sense. But it is not an obligation. A person can therefore have more than one Rabbi. He can also have a Rabbi for all questions and issues except for one. For example, the Gemara in Shabbat (22a) writes that Rava followed his Rabbi - who was called "Rav" - in everything except three cases. There is also a concept called "Rabo Muvhak," i.e. a Rabbi from whom one has acquired the majority of his wisdom (see Bava Metzia 33a). Nonetheless, there is a halachah in the Shulchan Aruch (Yoreh Deah 242:4) that it is forbidden for a person to give a halachic ruling or to establish a yeshiva without permission of "Rabo Muvhak." The exact wording is that one needs permission from one's foremost teachers – "Rabotav Ha-Muvhakim." But how can one have more than one "Rabo Muvhak" - after all a "Rabo Muvhak" is a Rabbi from whom one has acquired the majority of his wisdom?! The Shach explains there (#12) he has "Rabo Muvhak" in Torah, "Rabo Muvhak" in Gemara, "Rabo Muvhak" in Halachah, etc… We see from here that a person can have various Rabbis, each in a different area. The ideal is obviously for a person to have one Rabbi for everything so that he can have a unified system of thought and practice.