Yes, A, B, and C width Fender necks have always remained within +/- 1/16" tolerance of 1-1/2", 1-5/8" and 1-3/4" respectively, regardless of the year.
I haven't run into that much variation in nut widths I've measured (yes, I'm a nerd, for years I actually carried 2 inches of ruler in my wallet to measure them) and all have been the nominal widths for the time. The J's I've mesurred from the '60s through much of the '70s were all 1-7/16". Not saying there isn't that variation, just that I haven't seen it.