What are the guidelines for how often one may visit a jewish cemetery? Is there a difference for kivrei tzadikim? I heard one should not go more then once in thirty days, is there a source for this?
It is possible that different people have different minhagim, however what is brought in halacha is that one should not go to a specific kever to daven more than once a day. Meaning that once the person has finished davening what he wanted he shouldn’t go back to daven for other things that he forgot. Rather that the person should daven for whatever he needs before leaving the kever.
If however after the person left the kever, a new need came up, some poskim say that the person may go back to the kever to daven.
A person that is being paid to go to kevorim to daven, may go back to the kever again to daven for a different person.
Magen Avrohom 581-16, M:B ibid 27, Kitzur Shulchan Aruch 128-13, Nitei Gavriel Aveilus 88-2,3.