Atleast from my experience, its much easier to notice and pay attention to callous when they ping the area a player may be or an angle that they are holding. Of course you should pay attention to callous but I've definitely been in some sit...

I realise what a silly question I've asked, but I genuinely do want to know. Could there be some sort of limit/cap to a person's hand-eye-coordination abilities? My reason for asking is that I simply have terrible aim in any FPS game...