The 'control' built in is the dog working to catch the bird in your gun range. And from my experience a wild pheasant only runs as fast and as far as you push it. It flushes when it runs out of room, runs back into you, or gets too nervous from being tracked. Few stop and hide - albeit that's a bonus and I've found largely weather related.
The only downside to the dog believing it will catch the bird is the delivery of un-shot ones on the occasional game farm hunt.
And above all - Sit means Sit.