Why do pro-gamers spam hotkeys?

[LastPoet]

I've heard a pro gamer explain that doing this early on in the game keeps your fingers moving and more prepared for when you actually need to execute lots of commands later in the game

This. When I playyed SC and Brood War, at the start there wasn't much to do. Spammjng hotkeys early is like warming up to the mid to lategame. I only did 180-200 apm, not a progamer ofc.

Also square select several parts of the screen to calibrate the accuracy of selecting.