What's this?!

[Legate of Amon Lanc]

Gondor was, in some ways, an ideal state. A descendant of Númenor, the blessed land, as much as Arnor was. The feudals of Gondor were all responsible, caring of people, serving the crown - or later, the stewardship - and there was no rivalry between them in any ways, except for these moments, when there occured something like the schizm of Rómendacil&co., which you probably had in mind. Possibly there were some troubles over local little bits of country, but they all were solved peacefully by the judgement of the higher authority (the King or steward, or just some higher rank feudal), or merely by diplomatic ways. You have to consider however, that Gondor as being raised more or less to an "ideal state" in Middle-Earth would, possibly (methinks) mean that its inhabitants were according to the Christian standards of law (as Tolkien being Christian), meaning taking authorities as granted from God (in Middle-Earth, Eru, or Valar, or whatever). This would I think very well explain how it was possible that only one big problem occured, and that it was at the moment when there someone who would have normally inherited the crown was not actually up to the standard.