Coordinate trainer
Know every square on sight
Thirty seconds. Find the square you are asked for, as many times as you can. If you have to count a, b, c, d to find d4, that is working memory you are not spending on the position — and it is why long calculations fall apart. This is the drill that fixes it for good.
8
7
6
5
4
3
2
a1
b
c
d
e
f
g
h
Ready
Tap the square you are asked for. Thirty seconds on the clock.
Make it harder
Most players are only fluent from White’s side, then sit down as Black and lose it with the clock running. Labels off, from Black, is the real test.
Coordinates come up everywhere — the calculation gym gets much easier once the board has names you do not have to work out.