I went to a D3 and doing it over again would have went D1. I had options with two excellent D1 schools both with highly respected coaches. I may not have been scholarship level, but had times within the acceptable walk on level (4:15 mile).
Main reason is coaching. At the D3, I was self coached. Our CC coach was new and it was his first coaching job. He was 25 years old and a recent graduate of the school. He was nice but didnt know what he was doing. He made the workouts up in his head when we showed up to practice that day. One of the regular workouts was frisbee football. He was just a big kid, and acted like he was still in college. Screwing around, jumping around, etc..
Had a separate Track coach. One coach for the entire Track team. He was a throws coach and neglected the rest of the team.
We could barely get a 5 person team together for CC. In track, I was the only 1500M guy so mostly trained alone.
So I was a 18 - 21 year old self coached college kid that never developed to my full potential. Graduated D3 at 21 and went out into the working world, so running faded away. I did the the best I could but looking back I wasnt able to coach myself very well. This was several years ago so I had books but not the internet like today.
On another note, we did have a laundry service. It was a mesh bag, you filled it and dropped it off. The next day the bag would be on a hook and you would pick it up. I didnt realize this wasnt the norm!