I worked at an ISP call center for a few years, doing tech support. My numbers weren't great, in terms of calls handled per day. I can't recall the number anymore, but while I usually got close, it was always a near thing. At some point my brain would just go numb.
If anyone is curious sitting at a phone for hours a day is soul crushing. Just FYI.
We got two 15 minute breaks and a half hour lunch. One day I decided to start taking a short break after every few calls, trying to amortize my half hour of small break time out over the whole day. I'd like to say it was because I carefully plotted out what would help me the most, but I was essentially an insensate beast at that point and can only thank my subconscious for its brave effort to keep me from dying. Anyway, the day I started doing that my numbers nearly doubled, and remained high from there on. The key, it seems to me now, wasn't just that I wasn't working during my two to five minute breaks, but that I would actually get completely away from my work area. Go the bathroom, get some water, buy a soda, bother the smokers, whatever. If I just sat at my desk browsing the internet, I got nowhere near the same feeling.
It was a unique revelation for me. True, I was taking more break time than I was allotted, because I'm bad at tracking things like that, but nobody cared because my numbers, and caller satisfaction, were rather high.