I vaguely recall an early Oilhead service manual containing advice that maybe 30 minutes was the max for idling.

Of course the Police need more than that (and perhaps a fast idle) and those bikes have electric fans for the oil cooler.

Thing is, the amount of heat your motor generates is directly proportional to the amount of fuel burned, and it isn't burning much at idle. Diesels are even better in this regards as they vary the fuel-to-air ratio and at idle it's maybe 1-150 as opposed to the 1-15 (stoichiometric) gasoline engines usually run at. Some diesels come with software to boost idle speed should they overcool during extended idling.

So, when you're sitting at road construction, nervous throttle blipping only serves to put more heat in your engine.

Many are confused by old time American cars with water pump mounted radiator fans that did tend to overheat at idle. That's not applicable to aircooled engines and it doesn't happen.