Once my electrologist gets going I've timed her at roughly 15 roots per minute using Apilus thermo-electrolysis hardware. She doesn't really take a break during an hour or two. But she sees waaay more than I do - she has sharp eyes, a 10x magnifier and lighting designed for this type of work. I've gone in there for a couple dozen hairs and she finds a few hundred.
The really nice thing is once the larger roots are eliminated, it's not just visible stubble that's gone - the skin is so much smoother and looks different without all those roots below the surface. Skin is slightly translucent.