No way can someone feel that little of a difference. Given a blind test it would be "hope I guess the right one". Anyone that says that I'm sure can shoot 4" groups at 100 yards and uses the same pin for zero to 40 yards with no drop. It's an old tune when you been around archery for a long time.
when I was shooting competitively and on top of my game, I could notice one twist's difference, in my draw length, by how my release execution ran. granted my execution was very well developed after almost 30 years of shooting a hinge, at that time, bit I could notice that small a difference. one twist,..... how much does that change the length of a string ?....not much.
what you don't realize is that your body is extremely exact in it's control through subconscious process, in respect to "the feel", of the activity being controlled, when you do things like that on a repeated basis.
I spent 35 years working in the papermills doing millwright work, mostly precision shaft alignment. I got to the point that I could grab a piece of shim stock and feel if it was .003, or .005 as soon as I grabbed it. I regularly proved it, to guys when they'd call me on it. I could grab just about any piece of shimstock and tell them what thickness it was by feel and when they checked it with a mic',.... I wasn't wrong very often..
some people are just built that way and have that natural ability. it's almost like they are "more aware" of what they are doing, than others are. in my own wood shop, when working on the table saw, i'll slide the fence over to where I think it should be for a particular cut, lock it down and the check the measurement, and it's usually so close that I have to look real closely to see of it is "right on", or not. ive been able to all that sort of thing all my life, I can't even say that I remember just when I started being able to do it simply from experience....I was just able to do it, as far back as I can remember putzing around, as kid, in my dad's, shop as well..
in 3d, I regularly helped setting up the courses and i would simply take a quick glance at the shot, from one of the stakes and declare a yardage, then they'd take a rangefinder shot from the same stake . I was usually always within a yard or so, for a whole 28 station course, when I would estimate to the 1/2 yard. it got to be sort of a game, they would ask me to come along as a "beer challenge", to see of I was just lucky, or whether I could actually do it consistently. very seldom, did I buy them a beer when we got back to the clubhouse.