Once a week we get weight room time at a local community college. We do the 5x5 routine.
We mix in other sports once a week for cross training.... basketball drills for footwork and timing, handball for hand eye coordination, ultimate frisbee, and even football drills.
5x5 is a quality rep scheme for building strength. For HS athletes getting into the gym 1x a week, you should be able to keep a linear progression for a decent length of time. In other words, if the starting point is right, you should be able to add an incremental amount of weight each week for several months to each athlete's lifts, depending on their training history.
Good on you for mixing in the other sports in the off-season. I think it's important for building more well-rounded athletes and developing proprioception and kinesthetic awareness.