the older ages you go, the more life interferes with practices. especially 16 and 18u. Players start driving, jobs, boyfriends, doing nothing, band, choir, other school stuff, other sports, etc... All start to eat away from time available to practice. Regardless if the player really needs said practice or not. We all only get 24 hours per day.
And for the ones that go on to play college..... the distractions (besides classroom related stuff), all come to a screeching halt. that lame excuse to miss practice to hang with friend and make Tik Tok videos....gone. The I can't practice I have to work....gone. The must spend the next 7 hours texting boyfriend..... gone. Sure, there's time management issues in there, but the distractions get managed or the coach will manage the player to the bench.
My 18u teams practice 1x per week in August, then again come winter after all the fall season stuff complete. Usually 4 hours on Sunday afternoons. And then they are all in school ball purgatory starting Feb. And come back to travel team mid-late may. And then we are playing tourneys every weekend in summer.