How long should I cook pasta sauce? I recently made pasta sauce, and every couple of minutes decided to add something more... More tomatoes, more pepper, more garlic...
After that I let it sit on a small flame for a bit more.
As a result, the sauce set in the pot for a fairly long time (45 min at least).  

I asked my roommate if it's ok to leave it this long, and he said that the longer I leave it, the better it will come out.

Is this true? Is patience a key ingredient to a perfect sauce?
(P.S, it really did come out great...)
Yes, with any kind of 'stewing' sauce, the flavour improves the longer you cook it (provided it's a slow, gentle process). The longer you leave it, the more chance the flavours have to 'marry'. I have a recipe for a pasta sauce that calls for 6 hours of slow simmering!

You may also have noticed in the past that left over pasta sauce that you eat the next day is really good, for the same reason as above. Any stew, in fact, like bolognese, casserole, chilli, bourgignon etc, is really delicious when left overnight and reheated.