i get your point, but i have a different experience. i also believe you are missing that once you made friends, switching tracks will only make it slightly more difficult to keep in touch. i didn't make many friends in school, but the friends i did make were not limited to my class and track. i can still see them during breaks, and we still share the same routes to and from school, ad we may still participate in the same extracurricular activities or clubs. those things would not change when switching tracks.

separate physical schools however may mean that i may never see some of these friends ever again. different school routes (even if we live in the same neighborhood). no chance to meet in breaks, etc. that's a whole different world.