Every time I see one of these discussions I try to picture a solo pilot, faced with a sudden powerplant failure, pulling out his E6B and calculator so that he can accurately figure out the precise indicated airspeed to use to maximize his glide...

... for the 30 seconds since a minute later, the airplane will be lower, maybe turning toward a landing site (although maybe not with the pilot's head in the cockpit figuring out best speed) and the calculation will need to be done all over again.

I know. I know. I like an academic discussion as much as the next guy, but still...