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Stop watching your overall accuracy — find the three keys you keep missing

September 20, 2026 · about 736 words · Speed and accuracy

An accuracy figure tells you how much you are wrong. It does not tell you where you are wrong, and the where is the only part you can act on.

A typist at 96% accuracy sounds fine. But 96% often means: flawless on twenty-four keys, and a coin flip on three. Those three keys appear in a large share of words, which is why the typist's speed never quite reaches where it should. The average hides this completely.

Why averages mislead

Suppose you type 1,000 characters and get 40 wrong. As a percentage that is 96% accurate, and it looks like a uniform, slightly-sloppy performance.

Now break it down by key. The realistic version looks like this:

Three keys are 85% of the problem. Fix them and accuracy goes from 96% to 99.4% — and, more importantly, the stumble disappears from every word containing them.

Drilling "accuracy" in general would take months to produce that result. Drilling three specific keys produces it in a week.

What a heat map actually shows

The error heat map in the progress panel records which key you were *supposed* to press each time you pressed the wrong one, and colours the keyboard accordingly. Hot keys are where your errors concentrate.

Two details make it more useful than a simple error log:

• It measures error rate per opportunity, not raw error count. A key that appears rarely and is missed twice looks worse than a common key missed five times, which is backwards.
• It separates wrong key from wrong finger. Pressing the right key with the wrong finger counts as correct for accuracy, but it shows up as a reach problem, which is usually the real cause.

The four patterns worth recognising

1. A single key, consistently missed. Usually a reach problem — you are using the wrong finger for it, or your hand slides rather than extends. The fix is finger assignment, not repetition.

2. A cluster of adjacent keys. e/d/c all wrong, or u/j/m. This is almost always a hand-position drift: the whole hand sits slightly off from the home row, so one column is systematically mistargeted. Re-centre on F and J before each session.

3. Errors concentrated on the top row or bottom row. Suggests the wrist is tilting during the reach, or that you are reaching with the hand rather than the finger.

4. Errors that appear only at speed. Not a knowledge problem at all — a timing problem. The finger leaves before the previous key is finished. Slow down for a week; the pattern usually dissolves.

How to drill a problem key

The mistake is to start typing words containing it. That mixes the target key with every other key, so the signal you get is diluted and the drill takes far longer than necessary.

Do this instead, for five minutes a day:

1. The key alone, twenty times, slow and perfect.
2. Alternating with its home-row anchor — for c, alternate d c d c d c. This trains the reach *and* the return, and the return is what people neglect.
3. Three-letter groups containing it: cat, can, come, back.
4. Real sentences, last, once steps 1–3 are clean.

One week per key. Not three keys at once — under time pressure the old movement wins, and you end up reinforcing all three.

Why the return matters as much as the reach

Most people practise the trip out to a problem key and then relax. But the hand has to come back to the home row before the next keystroke, and a sloppy return means the following key is also mistargeted — which is why a single bad key often appears to cause errors on its neighbours.

Alternating drills (d c d c) fix this because the return is half the repetition.

When the heat map is lying to you

Two caveats:

• Small samples. If you have typed two paragraphs, the hot keys may just be the letters that happened to appear. Wait until you have a few thousand characters before drawing conclusions.
• Unfamiliar text. A passage full of uncommon words will show errors on keys that are fine in normal use, because you are hesitating on spelling rather than mistyping. Drill on ordinary prose for a clean signal.

Used properly, this is the single highest-leverage diagnostic in typing practice: a week on the worst key usually does more for your speed than a month of general practice.