Watch the Dust My Bass online guitar lesson by Jasper Mortier from 50 Blues Bass Licks You Must Know
During the (mega trademark) intro there's no quick change and after that in the verses and in the (also trademark) theme there's often a quick change. For determining if there's going to be a the quick change, you have to listen obviously. Plus look for eyecontact with the 'chord people' (keyboard, guitar) especially in the beginning of the song when things still have to settle. Robert Johnson was all by himself. So he was completely free to change chords whenever he felt like it. It's hardly ever exactly 12 bar. More like 11 and a half or 13 bars or whatever. But the way he changes feels completely natural to the listener. It's challenging to play along with him and follow his guitar licks and his singing. If you just listen it's not hard at all! In the 1951 Elmore James version, the bass player doesn't always seem to interact with what Elmore's playing. He switches between IV and I quite randomly it seems! Maybe there's some purists out there who will claim that's the real deal. But to me it's sounds a bit underrehearsed if I may say so. Or maybe they couldn't hear each other properly in the studio setting or maybe somebody in the control room just wanted things to be finished and released as soon as possible! Who knows! Still the overall result is super authentic, strong and groovy. Both versions show the roots of this music as spontaneous and open as it gets. A big contrast with the more current way of playing and recording music. A lot of Elmore James stuff nowadays is played by more power-rock-blues slide-guitarplayers and accompanying bands. But you still have a choice to play it more old school way too.