When I had a lot more time for gaming, I played in a number of what I call consistent RPG campaigns (although it's likely that there could be a better term), by which I mean campaigns where we played regularly (at least once a week) for a solid block of time (at least 6 months). This is my preferred way of gaming because you really get to know the characters (your own and the others) and the setting, and you get to really care about the game.
In many ways, this is the best way to roleplay--you can really build up great relationships with other characters and the setting, and it gets very easy to slip into playing your character. The best RPG campaign I ever played did exactly this. I played Vampire: the Masquerade for the first time in Chicago staring in '94, and we played that game at least once a week for nearly a year. I've never gotten so into a character, understood him so well. I've never had such great in-character relationships--hostile and friendly. No matter what its flaws, I'll always love Vampire in part because of this campaign.
This type of campaign can have a downside, though. A few years after the Vampire game, we started a Fading Suns game. All the ingredients for a repeat of the Vampire game was there--same group (for the most part), same GM, and even a game created by former White Wolf guys. After a good start, though, the game degenerated--it turned out that, despite being told by the GM to make a group of characters who would want to work together, two characters from the outset hated my character and/or lied to him (one decided during character creation that his character blamed mine for his father's death; the other decided to cheat me and several other PCs from the start). The hostility bubbled over fairly early and eventually the game became a grind--it was a weekly session of my character constantly arguing with everyone else, and eventually several PCs were actively plotting the deaths of others. The game ended ignominiously when half the party died on a lost world.
In case it's not obvious, this campaign still pisses me off after many years. I'm annoyed as hell that the GM let the others make these characters, given that he told us to make compatible characters. And I'm pissed at the other players for making such characters. It's incredibly petty for me to hold on to this, but I'm a petty man.
I suppose I can't blame the failings of the FS game on the consistent nature of the campaign--but the consistent nature of the campaign exacerbated the problems in the game. I guess the real point is that a consistent campaign makes a good game better, but a bad game worse.