In juco, I spoke to the coach to arrange his tryout, and a couple times the during two years regarding the photographs I gave to the college and parents. He invited me to come inside the fence to get closer to the action while taking photos, I politely declined - I never wanted to interject myself into my son's experience. There were issues, my son's training beliefs and regiment were counter to some of what the HC wanted to see. My son may have not have given max effort to some drills, but he worked after practice on the things he believed he needed for improvement and arm care. This certainly created internal friction, but I was never involved and they worked it out by the second year. We did exchange a texts last year, so I could leave him a MLB debut ball as a thank you.
I met the assistant coach at Arkansas, Tony V. at a restaurant in Houston some time after my son had committed and that was the first time I'd spoken to anyone from the school - never spoke to him again. I never saw any paperwork beyond a small bill for something the scholarship didn't cover. First time to Baum was for fall ball, and a short coach with a huge smile I'd never met, Wes Johnson called to me by name and said it was going to be a fun season - never spoke to him again, although he'd always wave (he did let my son incorporate his specific training regiment into the Arkansas program). Spoke to Van Horn for the first and only time at nearly the end of the season (SEC championships) - he was in the lobby of the Hotel, I introduced myself and thanked him.
It seems to me that every situation is different, but my goal was to be supportive and not part of my kids experience. Even in youth ball, unless there was physical and emotional abuse (I can only think of one occasion) then I was silent about all things coaching related.