Have you ever found yourself sitting down to knock out some emails, or just get some work done and one of your friends send you a funny youtube video... then you look at the clock to only realize you've spent an hour laughing your head off at some funny videos?
I have never done this, but I've had friends who have. (ha! ha!) I think if we are honest this (or something real similar) has happened to all of us at some time or another.
There are times I actually needed the break, and it refreshed me, but most the time I find myself "busy doing nothing" to only get to the end of an 8 hour day having accomplished NOTHING worth anything.
What I try to do: Plan my day, and then work my plan! Then at the end of my day I will have accomplished what I set out to accomplish... rather then another day gone by, busy doing nothing!