I used to sneak onto my local course all the time when I was a teenager, but the situation was a bit different. First, a bit of history. At the end of each school year the city parks and rec department held a class at the local YMCA for youth golfers in the area. The class covered the rules of golf and proper etiquette, and there was a test at the end. If you took the course and passed the test you got an "etiquette card" entitling you to 50% off the junior rate at 2 of the local muni courses (meaning $6 for 18 holes, sweet deal) for the rest of that year. So anyway, I lived right behind the 3rd tee of my local muni. One day during the summer I asked the manager in the clubhouse if after-hours practice was permitted. It was very common for people (non-golfers) to walk the course or even walk their dogs after hours, so simply being on the course obviously wasn't an issue. I told him I lived right next to the course and had my etiquette card, and I promised to leave the course in better condition than I found it when I walked on. He told me to have at it as long as I didn't cause any damage and made sure I waited until all paying groups had left the course. So I now had free and extremely convenient access to my own course for all the practice I could possibly want. Sometimes, just to sorta give back, I would grab a sand bottle off one of the carts and just walk the course, filling all the divots I could find and repairing ball marks left on the greens. It was really a fantastic arrangement for a junior golfer, and I really miss having such an opportunity.