Robert Johnson recording speed controversy

A controversial - erm, controversy - from 2008 (afore my time, by golly):

http://webcache.googleusercontent.com/search?q=cache:xBJ5VMngYNkJ:acrosstheuniverse.forumotion.com/t718-robert-johnson-recording-speed-controversy+site:acrosstheuniverse.forumotion.com+acrosstheuniverse.forumotion+blues&cd=26&hl=en&ct=clnk&gl=uk&source=www.google.co.uk

My two pennorth: why the hell would the ARC engineers deliberately mess about with the speed of the recording machine for this almost unknown young geezer and not for other folks recorded on the same sessions - well, nothing's been reported about other records from those dates being 'sped up'?

That's a reasonable explanation - the engineer just wants to make sure he doesn't waste too many blanks. But I seem to recall reading an analysis of the timing of Bob's 40+ takes, and the average time coming out so far short of 3:00 mins that the theory looks a bit silly. Poor Bob knew how to finish a number in his allotted time; din't need no engineer with a heavy hand fixin' it for him. I suppose we'll never know...