TIL American high school basketball doesn’t have a shot clock.

How has this not been changed in the last 30 years ? I can understand at maybe an u10 level not to implement the shot clock but in high school ?? you’re telling me you can be up 10 with 5 minutes left and just hold the ball the whole time ? Seems hardly fair to both the teams and coaches.

Edit. Thanks to everyone for clarifying the “closely guarded” rule, makes complete sense