5prong...
You are correct in that I did see several one prong 5 leafers in my 2 year old stuff, but the large majority were 2 prongs.
Some had 2 prongs with 3 leaves on both prongs, others had 3 on one and 5 on the other, and some had 5 on both sides.
I would say that 80% or more of my 2 year olds (of what is up now) were 2 prongs.
I do expect the gypsum has helped. I put it down when I planted, and again this spring (back in mid Feb).
I plan to put it down only once a year in Feb, instead of in the fall and spring like Scott suggest in his book.
As long as they continue to make progress like this, only once a year should be fine.
TNhunter