Tradition. Sometimes its a belief or behavior passed down within a group or society with symbolic meaning or special significance with origins in the past.
For me it's just a way to look busy while my company collapses into financial ruin around me -probably because I didn't get the hard drive controller drivers figured out on the HP 8300 minitowers. Why do they keep bailing on the Windows 7 image at 99%? We'll never know.
So, who's with me on a drinking binge at work this morning? Baileys smells like coffee -mix it on in there and they'll never know.