Wall balls are the last station: 100 reps before the finish line. Legs are gone, shoulders are tired, and the finish is close enough to hear. It is also where the most time is lost to no-reps and long rests.
Break early
The most useful rule is to break before you have to. If you can do 30 unbroken when fresh, you probably cannot at the end of a race. Plan sets that you can hold — for example 10 sets of 10, or sets of 15 then 10 — with short, fixed rests between them.
Short, planned rests are much faster than going until failure and then needing a long break.
Keep rests short
Rest for a few breaths, not longer. Count them. Hold the ball at your chest while resting rather than dropping it, so you do not have to pick it up again.
The movement
Squat below parallel, stand up and throw the ball in one movement, hitting the target. Catch it and go straight into the next squat. The legs do most of the work; the arms guide the ball. Use the catch to start the next squat, not as a separate movement.
No-reps
The common faults are not squatting deep enough and the ball not hitting the target. The judge will tell you, and the rep does not count. When you are tired, it is easy to cut the squat short. Focus on depth, especially in the last sets.
Consistent throw
Throw to the same spot every time. A ball that hits higher or lower on the target comes back differently and breaks your rhythm.
Breathing
Breathe out as you throw and in as you catch and squat.
Shoes
A flat, stable shoe is better here than a soft one. Very soft shoes can feel unstable in the squat. See stack height and stability.
Training it
Do wall balls at the end of long sessions, when you are tired. Practise your set plan so it is automatic on race day. Wall ball conditioning has a progression for building volume.
Finish
When you finish the 100th rep, go straight to the finish line. There is no run after the wall balls — you are done.