Are meetings mandatory?
No. None of the meetings are "mandatory". Once a candidate has been raised to the 3rd degree, participation is completely voluntary and at the individuals will and pleasure. Further, a Mason is not obligated to go only to his lodge once all 3 degrees have been obtained and a certain degree of proficiency has been achieved. Once full membership is achieved, the Mason can go to any lodge or Masonic function.
There are certain protocols when visiting distant lodges.