When I competed in NCAA gymnastics there was a chance we would get tested every month. The athletic trainers really only focus on the big sports we were after thoughts and more of an annoyance to them really. Only sure way we knew we were going to be tested is if we qualified for nationals. Do good at nationals you qualify to be on the team that goes to Worlds, and then the Olympic Committee gets involved. There's a lot more money in sports like football, basketball, baseball, and track though, so I don't know how they do it, but I will say I heard the way tests were done at my university is the trainer would ask the coach who they wanted tested, and coach would just send who he knows would test clean, so the same damn guy was pissing in a cup every month.