Soccer is extremely popular in my area. There aren't enough open fields. The large soccer clubs rent fields from different organizations (city, county, etc.) including the school districts. Generally from 4-7pm the high school fields are rented out to youth soccer clubs for practices M-F. From 7-10pm they are rented out to adult leagues and are fully lighted. This runs from about Sep through May. I've seen a number of runners stop by the track when the adults are playing soccer to do interval workouts. Never heard of anyone being asked to leave. Just need to keep your eyes open for any errant soccer balls.