You watch a dull square for a long stretch. Click only when it turns pure black. Nothing else counts.
Why it is useful
Driving is hours of almost nothing, then a change that matters. Operators need people who stay on the display when there is no plot. Misses and false alarms both count. Five minutes is easy. The second half of a long run is the real test, which is why short bursts at the kitchen table do not train it.
A target shape and colour, then a busy grid. Mark every match. Some rounds have none.
Why it is useful
Cab and lineside are busy fields. You have to see the thing that matches and ignore near-misses. Empty grids exist. Clicking because the clock is loud is a fail mode. A methodical scan beats a heroic stare.
Click when the circle turns green. Do nothing when it turns red.
Why it is useful
Fast is useless on the wrong signal. A driver who is slow to a genuine change is a problem. A driver who treats every flicker as a genuine change is also a problem. The test is withhold as much as go. If you only watch your best time, you are watching the wrong number.
Timed operational questions: faults, signals, and what to do next.
Why it is useful
Selection is not only staring at squares. You also have to pick a safe next step against the clock. The dramatic answer is often worse than the boring one: stop, protect, tell someone. Practice here is for the type of decision, not a leaked paper.