Cantus stated that they travel around, uniting the Rock with music. The troupe includes beings from at least three different colonies, probably four, as Brio and Cantus look like different subspecies of Fraggle. The first time we saw Cantus was on his first visit to the colony that we know. He has also stated, when asked if there are only five minstrels, "As far as I know, and I know pretty far."
All that implies pretty strongly to me that this little band of minstrels travels through a very wide, varied territory, and visits as many colonies of sapients as it can so as to spread enlightenment. It doesn't seem likely that they stay in one place very often. Considering that several times Cantus has appeared without the other Minstrels showed that he will travel alone, even in the dead of winter, so perhaps the others sometimes take a vacation with their loved one.
I can think of a number of circumstances that might cause the minstrels to stay in one place for a while. If one became sick or injured, I can't see the others just leaving him or her behind; it's not like they've printed up tour schedules. External dangers might make it unsafe to leave, for example a plague of strangleweed or a population explosion among Rock Clingers. Or their mission might require them to stick around for a while--say, if some particular Fraggle needs to find her song or Cantus has some other point to hammer through.