I went to college later than the typical 18 year old. I worked after graduating high school, knowing I would just get drunk as often as possible in college. We had no xc or track programs in my high school, so I never really had much interest. However, I was only a p/t student, and had very little money, so out of necessity, ran to/from work and sometimes school. Without knowing it, I built a two year base of running four or five days a week, at what I would now estimate as 2-4 miles each way for school and 3to4 miles each way for my job. I took 7 1/2 years to graduate. I ran in some races during my years in college, and quickly realized I needed help. first, I am too competitive to accept being beat by older women. Second, I was too slow for my own satisfaction. I started actually training, got real race flats, didn't stay in trainers all day and changed shoes after 500 miles. I was running about 34:30 - 35:00 for a 10k. by the time I graduated, I was in the mid 32's. I went to grad school and found people who actually knew how to train. I followed them, and got much faster. I ran 31:10 on my 31st birthday.
So, yes, I broke 32 min after college. But it certainly was not the conventional route.