Agree about the hunting alone part, not so much about the distance/ranging part. Sounds like I would have been dead a long time ago if we hunted together Reddog.
I hunt flushers, and I keep them close. Close not because they are lazy, but because that is where I want them. 35 yards might work for some guys, and maybe it's because i'm a tad slow, but it takes me a second or two to get on a bird once my dog puts it up. 35 yards plus 1 second pretty much puts that bird out of range for me.
I also don't get around as well as most guys because of an injury from years ago so I don't cover as much ground as some. The places I hunt most of the time are very, very heavily pressured public grounds. I can't compete with the guys with good pointers that can let them run 150 yard patterns across the big fields. Instead, I hunt more tactically and look for edges, small pieces of heavy cover, etc. where it is often to my advantage that the dogs work close or precisely. I shot a rooster last fall in South Dakota out of a spot of taller grass no bigger than a kitchen table top because I directed Sage to that tiny piece of cover.
It's just what works for me, and I train my dogs according to the way I like to hunt. Its about me and my dogs, nobody else. To each his own.
Back to the original post question - I hunted SD for my first time ever last year and I hunted the end of the first week of the season. I was very satisfied with my hunt but very few crops were harvested and a I saw just a ton of birds in and out of the crop fields. I watched a guy harvest a sunflower field adjacent to where I was hunting and i was just amazed at the number of birds that piled out of there when the combine came by.
So from a rookie, look at it two ways. Hunt early in the season and the birds aren't yet as educated and there are just plain more birds around, but they are distributed over a LOT of cover. The later in the season, the birds are more educated and there are less of them but they would be more concentrated than early on, especially if there was a little snow cover.