The need for a true blind, whether in the tree or on the ground, goes up in direct proportion to your ability to sit still and the availability of natural features to break your outline. If you can break your shape in any way at all and sit rock still, the deer just can't seem to see you.
I'm dealing with really mobile deer. Here one day and over the next mountain tomorrow. You can find hot spots that might be good at the moment, but coming back to them tomorrow is low percentage.
As a result of all that, when I find a spot worth watching, I find the nearest thing- tree, rock stump tall grass, berry stalks, whatever and sit down against it or in it, as the case may be.
Anything to break my outline. And when I reach the point I can't stand to sit still another minute, it's back on my feet. Wind in my face, and on any day there's a little sun, hopefully I can put it at my back so the deer are looking into the sun when they look my way.