I'm just gonna tell ya this. Sometimes in life a shot is not about ranges or how many miles per hour they're moving or what angle they're flying in. Its about knowing a Canada goose or whatever it is you're hunting. Yes all those factors like wind blowing your shot, ranges, shot size, and lead, as you said are extremely important. But this is certain; you need to miss the ball before you hit it. I guess the only way I think I can help ya is by tellin' ya to keep shooting. I'm no pro shooter. I miss more than I hit by a long shot. And I mean long-shot. Missing is just something you have to get over with and is something a lot of people don't like to admit to. The biggest reason people miss geese in my opinion is exactly what you stated. I just tell people you can't shoot too far in front of a dove or a goose. I read a dove article that stated the average dove shooter takes something like 8 shots per dove. That isn't hard to believe is it? A dove in flight is probably what? More than 10" with tail feathers and most of its body being a kill zone beings they're so fragile. Now take a 12 pound Canada goose, 3 times as long at least. Plenty of down, fat, and a lot more meat and bone with a lot smaller kill zone body wise. The dove is just plain harder to hit and that honkers harder to hit, plus, another 3/4's questioning being hit hard enough! Not to mention the loss in shot. Take a 1 1/8Oz load of 7 1/2's or 8's to a load of 1 3/8Oz BB or BBB. While I'm at it lets put all specifics into play. Picture if you will a dove flying over you 30MPH. Now that 12 pound goose at the same speed. Put that all together, shot to bird ratio has to be close to the same as that of a dove right? Trying to think about all this bull is too much to think about when a birds coming in. We've all had days when we made that one shot. Just an outstanding shot and we try to remember how to duplicate it when we should be thinking more about the shot you're being delt with. Every shot is different. The next one that comes in, you just focus on its head or bill. Hunting is practice
good luck
