assuming you are putting the 580 grip on a 580 shaft, 3 wraps will give you 1/32"= .031" over standard. so if 1/16"=.062" is considered midsize you are half way. each additional wrap will give you 1/64"=.015". if you are putting the 580 grip on a 600 shaft you are allready 1/64", over so 2 additional wraps will do it.
So, that's assuming the grip tape is .010" thick (or so)?
But, if you're using 2" wide tape and wrapping it around the shaft lengthwise, aren't you actually adding double the thickness, or one layer on opposite sides of the shaft? That .010" is now .020" for each wrap, 3 wraps placed over each other (remember to stagger/rotate the seams on the tape layers) is actually now .060", pretty damn close to 1/16th of an inch. If you're using 1/2" wide tape and doing a spiral wrap, with 1/2" between each spirall, then you're efectively only adding the tape to one side of the shaft or the other, correct?
Unless the grip tape is only .005-.006" thick, then your above statement of 3 wraps equaling .031" is correct. But, for some reason, it just doesn't seem like it would take 160-200 strips of tape on top of each other to equal 1". (.005"x200=1.000", .006"X160=.960")
Don't want to come across as an ass, just trying to play Devil's advocate
and learn something in the process.