Think of yourself out in the heat...
If you just stand still in the sun, you'll melt...
.. a comfortable strolling pace, and you feel some air movement...
.. but, try to set a mile record you'll blow a gasket..
Idling for more than a few minutes in heat is tough on the bike... a 20 minute or longer traffic jam will make your engine stall and possibly seize... I shut off in those situations, maybe pull over...
... but running at half throttle or above, is hard too...
Your bike is at it's most efficient and runs coolest at an easy lope... This is when the engine draws it's highest vacuum, and you burn the least fuel per mile...
... perhaps it is at it's coolest there, because it's burning the least fuel per mile... and, fuel = energy= heat... that speed will give you the most air-cooling vs fuel burned ratio...
This isn't just bikes or air-cooled engines... when I ride up Mt.Lemmon (near me)... from 2600ft to 9,000ft in 30 miles,... there are a surprising number of overheated modern water-cooled cars pulled over with the hood up... and my bike is still putting along fine, because I'm riding in her sweet spot... about 40mph in 4th, 50 in 5th...
Okay,.. now I'm just rambling....
...
The point is,... least fuel burned per mile = most cooling... 50 to 60 mph in 5th gear...
To cool a bike that is overheated,... the best option is to run in that sweet spot, if you can (45 to 60mph in 5th, 35 to 50 in 4th, etc... no lugging, no revving)... if that's not possible,.. don't idle, shut it off immediately... and hope for the best...