Yes it’s a part of cycling etiquet. With groups of riders on the road for several hours, it’s convention among cyclists to stop for a break at convenient locations.
However, it’s also good to have some consideration about where to take a break. Some locations seem to be “natural” stopping points form a riders point of view.
Rumour has it that the people who live around Highland Home (Apiti loop, Pohangina Valley) are complaining about the number of cyclists having a “Pissoir Natural” at the Totara Reserve intersection.
By all means, do what comes naturally, but consider the locals too…