It might... In theory, the small pin gives you a smaller aiming point and the smaller peephole diameter gives you less margin of error. But that only works if your eyes are young enough and good enough to see that itty bitty pin out there, thru that itty bitty peep.

Heck, my eyes aren't good enough to see any size pin any more, even without a peep in front of my eye! Well, it did get to the point where I found I could shoot better without the sights than I could with 'em.

Anyway...

I used to customize my peeps. I'd get a Fletcher TruPeep, the smallest size they make. Then I'd go to the range with a set of small drills, up to 1/16", and try to put myself into the worst shooting light conditions I could manage, both in the dark and glaring sun. I'd take a drill out and open up the hole in the peep a bit. Draw and look through to check it. Upsize to the next drill and check. Upsize again. I'd keep at it until the peep was just big enough for me to see clearly under the worst lighting conditions. Then I'd take a magic marker and black out the bright metal again.

Pin size... That's mostly personal preference and what best works for your vision.