Two minutes is long enough to show whether your speed holds up after the first burst.
Most people type fastest in the first 20 or 30 seconds. A two-minute test shows what happens after that: whether your rhythm stays even, and whether mistakes start to creep in as your attention drifts. The results page plots your speed second by second, so a fade is easy to spot.
If your two-minute speed is close to your one-minute speed, you are ready for the longer tests that schools and employers use.
Take one test and look at the speed chart on the results page. If the line drops in the second minute, the cause is usually one of three things: you started faster than you can keep up, you lost your place on a long word, or you stopped to fix several mistakes in a row. The time cards under the score show which one it was and how many words per minute it cost.
Then spend a few minutes on the drill built from your slowest keys and take the test again. Comparing two runs on the same day tells you whether a change helped; comparing your results over a few weeks shows real progress, because a single test can be off by several words per minute either way.
It is usually a little lower. A gap of a few words per minute is normal.
Many employers ask for a test of five minutes; try the 5-minute test once two minutes feels comfortable.