Anyone compared the span of the fingers on both hands, i.e. the distance that you can straddle from the thumb to the little finger at full stretch?

I'm right-handed, and the span on my left (fretting) hand is 22.5cm - and the span on my right (picking) hand is 20.5cm. Two centimetres difference - through playing the guitar for 45+ years!

The finger length on both hands is identical - I'm just exercising the left hand by stretching it more than I am the right hand.

Try it - and let's compare spans rather than lengths... :-)