Depending on where, when, and how you hunt, flushes may or may not be all that much longer than you're used to. Early season prairie grouse (sharpies and chickens) often sit pretty tight. You get into late Oct/Nov, when pheasant seasons are open everywhere, those grouse are in big groups and much harder to approach.
Pheasants . . . very much dependent on the cover you're hunting, your dogs, big group or just a couple guys. Lots of variables. At one point, I owned a pair of Army & Navy 12's (made by Scott). #1 was choked 005/015, #2 005/025. Never used anything more than 1 1/8 oz 6's, and that was in the tight barrel. Used the Kent Gamebore 1 1/16 oz Brit 6's in the open barrel. Very effective. But most of my hunting is small groups behind good pointing dogs. Private ground, and although it's not leased or anything to which I have exclusive access, hunting pressure isn't too heavy.
About the time you think you have pheasants figured out, they'll cross you up. Choke tubes can be a good idea, to adjust to conditions and bird behavior. About the only problem is, you screw in the tight choke and they all start flushing in your face. Good reason to have one open choke and one a good bit tighter--and two triggers, so you can choose instantly.
