A beginner types in bursts: a familiar word flies out, then comes a pause, then the next burst. An experienced typist types evenly, and an even pace ends up faster even when a single word takes longer.
The reason is simple: the pause is always longer than the gain the burst produced. During the pause the hand is looking for its place or the eye is looking for a key, and either costs more than a few slower letters.
Practise deliberately slower than you can. Pick a pace at which nothing gets stuck, and hold it for the whole line. The speed arrives on its own once the unevenness is gone.
The drill uses ordinary words of similar length, so the pace can stay even as the words change.