I don't actively "track" my higher level employees but I do tend to notice after a while which people always respond right away and which ones take a long time and never seem to be available.
At the end of the day I judge them on the quantity and quality of their work.
But if someone's not hitting their deadlines and they make some dumb excuse, I have no qualms about telling them to stop fucking around.
My entry level employees get tracked though. Not by some secret spyware or anything but just by monitoring their output. My data entry people better complete a certain number of entries per hour. My customer service people better answer so many calls per hour, or be in an available status.
My sales people get to goof off the most. Because as long as they hit their quotas then I don't care what else they do. But oddly enough, they usually end up being the hardest workers because that want that big commission check.