It's only a possibility at 14U and the number of 14U high schoolers is very low. all leagues for 15U+ start play after the end of the HS season. There is only one Triple Crown Tournament during HS season for 14U so some families choose to play that if there's no conflict with the HS schedule.
Truth be told, the HS coaches want a clear, bright line between HS and Club and want a kid's undivided effort during the very short season. I agree with this and so does the man that runs our Club program. He has been dealing with the situation for years and sat down with me to lay things out.
"For a 14 year old freshy, all effort and attention devoted to HS program, coaches, and games from the first day of tryouts through the last day of the season. If the school provides a "C" or freshman team and the kid is deposited there, enjoy the ride but try to make a few Sunday afternoon practices with the club. If the kid makes V, JV, or looks like he'll float between these and freshman team, then email me to let me know how it's going and I'll see you after HS season ends."
For upperclassmen, it's all HS team, all the time between the first day of tryouts and the last day of the season. No concurrent schedules so no issue of bouncing back and forth.
In my opinion these are superior scenarios to other boys and girls sports where select and HS seasons overlap. I've heard of all sorts of ultimatums levied by girls Volleyball clubs and soccer teams for both boys and girls. If you want to play schools, you won't be on our club. Now that has to suck.