Where the name comes from
The name comes from Aim Lab's Gridshot scenario, where three targets are live on a grid of fixed positions and each hit spawns a new one somewhere else. It became the generic name for the format, and most trainers have a version.
AimBetween's Gridshot mode keeps three targets active for the whole round and scores hits multiplied by accuracy. Rounds default to 30 seconds and there is a ranked leaderboard for it.
What it actually trains
On the surface it is a clicking-speed test. The clicking is the easy part. What separates scores is a loop that runs several times a second: see all three targets, pick one, move, click, and start the next pick before the current click has landed.
Most players who plateau in gridshot have a selection problem rather than an aim problem. Their mouse travels farther than it needs to, the path doubles back on itself, and there are tiny dead pauses after each hit while they decide what is next.
Order beats speed
Pick an order and keep it. Nearest-first minimizes travel, oldest-first keeps the board from piling up, and either one beats deciding fresh every time. A steady rhythm through a consistent path scores higher than bursts of speed with pauses between them.
Because the score is hits times accuracy, misses cost double: a wasted click and the time it took. A round of 90 hits at 95 percent accuracy beats a round of 100 hits at 80 percent.
How it fits with the other modes
Gridshot is the target-switching mode. Flick trains one committed movement onto one target, tracking trains staying attached to a moving one, and gridshot trains choosing the next target while you are still finishing the last. The 10-minute warmup slots it in after the flick block for exactly that reason.