I have a Brittany that I don't let out alone or she will run, run, run. I exercise her (hard, not just walking on a leash) 1-2 hours a day, and found that she tends to be difficult to discipline unless I work on it constantly and exercise her a lot. She is a fabulous hunting dog (we hunt > 100 days a year). I don't know about Irish setters, but I always thought dogs behaved better when tired out and that discipline was the master's responsibility, not the dog's.
Joe