engine driven fan was what I meant so the comparison isn't quite parallel but that is my experience with air-cooled. ultimately with my stop & go riding, what is best for my engine (750)? Is heat the enemy, and am I creating more chugging a little or at higher rpms?
To me, the average operating range is 3500 to 6000. Below that is lugging, above is not necessary unless you're trying to prove something.
On a really hot day, keep to the lower rpms without lugging if you can't keep the forward motion up (stop and go traffic). If you're moving along consistently rev it up more.
Engineers try to design for all contingencies. But a really hot day (90+ Faren) in stop and go, may call for a pullover once in a while. But I remember once in AZ going N to Phoenix at 105+ Faren, at speed the side wind blowing through the engine heated my leg past comfort. Not much one can do in the extreme, pulling over wasn't any cooler than keeping moving, at least for me.
A lot of hi temp stop and go would call for more frequent oil changes. I think.