It needs some way of clearing all data. I chose "don't know" on calibration because I couldn't be bothered to try to work it out (but my mouse will be on the low end because it's just some random cheap mouse). Then, the training was ridiculous having to move my mouse miles between targets, but there's no way to change the initial calibration step. Not even in settings / data / delete.

I'm not really the target user though. I guess those who are will already know exactly how many DPI their mice are.