Measure your drag clicking speed in CPS. Drag a finger across the button and see how high the burst goes.
As your finger drags across the button, friction causes the switch to bounce open and closed rapidly, and the browser counts each of those as a click. That's why a single drag can rack up dozens of clicks at once.
A 5-second window suits drag clicking, since it's about short explosive bursts rather than sustained rhythm. Expect numbers to vary a lot between attempts and between mice — that's the nature of the technique.
Drag clicking is dragging a finger across the mouse button so friction makes it actuate many times in a fraction of a second. It can produce huge CPS spikes — often 20, 30 or more — far beyond normal clicking.
Drag clicking depends heavily on the mouse surface, your skin and grip, so results swing wildly. Some mice 'grip' well and register big bursts; others barely register at all. That variability is normal for this technique.
It's the hardest technique on hardware — the rapid actuations wear switches quickly and frequently lead to chatter. Many players use a dedicated mouse for it. Check for double-firing on the double-click test.