Reading the alternation score
Put index and middle finger on the left button and let them take turns. The two fingers are never the same distance from the switch, so the gaps come out short, long, short, long. That rhythm is the fingerprint of butterfly clicking, and it is what the Alternation box measures.
Technically it is the lag-1 autocorrelation of your gaps with the sign flipped. At 0 each gap tells you nothing about the next one. At 1 every short gap is followed by a long one without fail. A run gets the Butterfly label at 0.30 or higher, as long as the rate is at least 7 clicks a second. The simulated butterfly runs I tested it with score 0.7 and up. Real hands are messier, so expect less.
Here is the counter-intuitive part: the better your butterfly gets, the lower this score can go. When both fingers reach exactly the same spacing the short-long pattern disappears and the detector reports Fast and even. That isn't a failure. It is what good two-finger clicking looks like in the numbers.
Double clicks and server rules
Some mice fire twice on a single butterfly press, because the switch bounces and the firmware debounce time is short. Players look for this on purpose, since it doubles their CPS. On this test it shows up as a pile of gaps under 30 ms, and the label changes to drag click or double-firing.
Before you take the technique into a game, read the server rules. Plenty of Minecraft servers treat double-clicking mice as cheating, and many flag anything sustained above 15 to 20 CPS whatever the method. A score here is about your hands. It is not permission from anyone's anti-cheat.
Getting the handoff clean
- Start slower than you think you need to. Six clicks a second with a perfectly even handoff beats ten with one finger doing most of the work.
- Watch cadence together with alternation. Alternation high and cadence low means one finger is late every time.
- Use the 30 second mode once the 10 feels easy. The Second half box shows whether the pattern survives when you get tired.