well, your body develops until roughly 25, so you should improve even with identical training from hs to college. You are stronger and smarter (hopefully lol).
Example, I had great training in high school and did great, I was state champ in mile 2x, xc 2x, team xc 2. college I was hurt a lot and had poor training. I still ran slightly faster than high school.
will always wonder if I could have stayed uninjured what I could have run.