Players 1 and 4 dribbles the ball to the free throw line and passes the ball to the person standing on the side of the court, who immediately throws the ball back. The player then dribbles to the half way line and repeat. The players on the other side are repeating the practice going the opposite direction.
Rebounding is the least glamorous thing in basketball and one of the most decisive. It is also almost entirely a habit, which means it is entirely coachable.
Good spacing is only the start. The best modern offences teach players to attack the defence's rotations and play in a permanent 4-on-3 - here is how to coach that read.
The ball screen produces almost half of all professional offensive possessions, yet most teams still teach it as a memorised play. The modern approach trains the read - giving players a framework to decide based on what the defence does, not what the coach called.