No. I think around 250 employees is in many locations considered large company. And above 500 or 1000 would certainly be such. So anyone with thousands such devices outside refresh cycle is certainly not medium sized.
There are tremendous outliers here, although this feels like a good occasion to bring up the class size paradox: The vast majority of corps are small, but since so many people work for the extremely large ones, it may seem like they tend to be on the large side.
If you're asking how many people work in some large corp, I don't see a paradox. The corp size also doesn't matter here. There's 1 thrown away Win10 PC per employee whether it's a 100K employee company or 10 employees.
