Standard Riff 5 uses the 5th blues position.
That one is not often used in “down home” blues, because some of the notes are kind of tricky to play.
You need to bring in your pinky and move around quite a bit.
But it’s a nice position to feature some more major sounding licks and the mixolydian scale is right beneath your fingertips.
This same standard riff position which was used in solo 7.