I work in short burst -- maximum 2 hours at a time. After 2 hours, even if my legs weren't tired, I would starting to lose focus. I would then take 15 - 30 mins break to have a tea/walk my dog/yoga/weight lift/talk to spouse/jump rope/shoot hoops, and then continue back again.
3G internet connection => Hardline
Living in suburbs => Living in the city center