It has been suggested to me that idling for extended periods of time is not good for the engine because the engine does not rid it self of excess heat that well if standing still. Excess heat is bad for engines in general. Maybe the Airhead engine can do this better than some other engine designs but it is still not recommended as a regular diet. I think it prudent to try and not idle the engine for extended periods of time.
About the only time I might want to have the engine idling for a longer period of time is when balancing the carbs. I am able to balance the carbs with out idling longer than a couple of minutes. If I need more time than this I take the bike out and ride some, then adjust some, then ride some.
I have been stuck in traffic a few times and the bike did seem to be over heated. I rode on the apron or the break down lane to the next exit. The bike was fine after words but it ran funny while it was over heated.
The advice about not over heating the engine is not original to me. I have heard this advice from people with much more experience than I have. I have always considered this good advice.
The box fan may be helpful to some riders sometimes. I don't have one.