Pretty sure you get two points if you hit it quicker. So if you let the dot rotate around to get the segment the next time you miss out.

You can get more than 2 if you hit two in quick succession. I think the max is 5 (tested with blind double-clicks until I hit two in a row).

You get 5 points if you tap twice within 0.5 seconds, and 2 if the interval is within 1 second. The source code is very readable.

    this.score = this.score + (tapInterval < 500 ? 5 : tapInterval < 1000 ? 2 : 1);

Seems to be correlated with how much time passed between two hits.