You can evaluate athlete / players as often as you’d prefer. For example. If you wanted to show the players their evaluation when coming into your program and if you/they wanted to track their progress monthly, re-evaluate them in one month and compare results. Some programs do an evaluation when the season starts and then does an exit evaluation at the end of the season to high-light what skills to work on in the off-season. There is no prescribed frequency as to when and how often evaluations need to occur.