People sometimes ask me "Phil, why are you such a deadly shot on upland birds?" Well, okay, they don't really ask me that, not even after they have seen me in the field, but if anyone ever did ask, I have the answer, and I learned it in driver's ed.
"Aim high in steering," they taught us, meaning, look down the road, not at the asphalt in front of your bumper. Whether you hunt with pointers, flushers or no dog at all, being ready for the flush so you can react to it is a very important skill. If your eyes are down on the ground a flushing bird looks like a blur getting up and out of your vision. You're behind it and rushing before you ever move the gun. It drives me nuts when I take people hunting and they trudge along staring at their toes.
If your eyes are up so you're "getting the big picture" (as, again, they taught us in driver's ed) you hear the bird flush, then it flies up into your vision. It's not a blur then. You see it clearly and react to it with a certain amount of composure.
Also, when you drive, you're in a state of constant but low-key vigilance. You might be listening to the radio or talking to a passenger (notice I didn't say "texting") but you're also always paying attention to the road and you're ready to react to potential hazards. The same is true with upland hunting. With every step I take I can imagine a bird getting up and I am looking where I expect to see it. That thought doesn't occupy 100% of my attention. I can talk or work the dog or enjoy the scenery, but one small part of my mind is always thinking a bird is about to flush and as a result, I'm still a little surprised when it happens but I'm ready, too.