This is very informal; it may be spontaneous (Hey! Let's break for coffee) or institutionalized (The coffee break in our office is from 3: 30-3: 50 daily).
It's not hard to see a through-line from coffeed-up workers keeping up with the pace of the machines in the factories, to the rise of office culture and the establishment of the coffee break in the 1950s.
Floyd's suffering inflicted by a cop who has the demeanor of a man on coffee break is what enrages, unites, and ultimately focuses those committed to change.