I believe the premise is that House’s team gets all the cases that nobody else can figure out, which is why they all funnel to him; by that point, they’ve got a chart full of H&Ps and whatnot.
It’s funny - I thought the entire show was contrived at first, but a doctor/prof of mine got me believing it wasn’t all that implausible (just, we’ll say, dramatized).
I can’t stand the soap opera aspects to it, though :P. It seems that’s where a show goes when they run out of other interesting ideas, but it just doesn’t do it for me. Fortunately, I think they’ve also done a good job developing the characters and showing different aspects of their interactions. And yeah, Wilson is my favorite ;).
HOUSE is my one televisual vice… 
Tim