I shot a doe from the ground this fall. I was in camo (but no enclosed blind, no ghillie), in a marsh, standing up next to a tree. The set up included waist high grass, an old fallen tree across the front of me, providing a sort of front, and a trail that ran across the front, about 5-6 yards away at its closest.
She came fast, from the right and I let her get too close. She heard me draw, stopped and raised her ears. Then took another step or two which put her head behind the grass and her body exposed. Bad mistake on her part, but planned on my part. I finished the draw, aimed and hit her where I aimed (even I can hit at 6 yards).
Again, yes, they can be too close, that is part of your learning, but if you have a bush, tall grass, a tree, a small chunk of wood soaked in scent and tossed into the grass on the far side of the trail, SOMETHING to eclipse their view or make them look away, you have a chance.
ChuckC