It is speculation, and probably not completely accurate but it does give people an idea of how hard P5 scholarships are to earn.
Some things to consider though--
P5s ask 1:54 guys to walk on for the most part and mid majors offer a partial at that time. The 800m has very limited utility outside of indoor on the men's side.
3.6 is a good guess on scholarships towards distance, but I do think many "well balanced programs" go up to 4.2 and some distance focused programs will go a lot higher.
A lot of really good P5 state schools will have no one on full rides, but a lot of times they will have 3-4 of their best American XC runners on 50-60% with additionaly academic based aid. American runners are often much more affordable than internationals and thus most of the exclusively international rosters are mid-majors trying to be nationally relevant.
A lot of good P5 programs will give out books to the 4:15/9:20 athletes. It is only .03-.05 scholarship at most schools so it is inexpensive and can help sell a recruit (makes them feel like a scholarship athlete). If you have a lot of athletes in that range some will develop.