The initial goal is to produce a basic counter which is superior to the original. In the design it is intended that the gearbox be adaptable to some sort of cable-driven rig for handlebar mounting. But that is the secondary goal, not the primary.
The Veeder-Root counter has a stated limit of 500 rpm, which translates into 5000 counts per minute. The higher the gear ratio, the smaller is the measured length for one count - giving more precision. But also increasing the speed of the counter.
I haven't heard of anybody destroying a counter by overspeed yet, but from time to time, especially on downhills, we all exceed the design limit of the counter.
See Speed Limits for more on this.