Why does the level require a minimum speed to progress?
Actually, it does not. The minimum speed of each level decides whether an exercise counts as passed and what reward you get, but it does not block your progress. To level up, you only need two things: practice volume and accuracy.
What each level really asks of you
- Accumulate the keystrokes required by the level.
- Pass the minimum accuracy at least twice.
Speed comes on its own with volume: it is a consequence of practice, not a toll. That is why the system does not punish you for going slow, it just asks you to practice more.
If you see that the level does not unlock even though you have done many exercises, look at the level progress bar: it tells you what you are missing. And if you are in a school, the teachers may have activated extra requirements, such as spreading the practice over two different days.