Congrats on getting up to step #15, that’s good going!
The riffs that are played over the 1 and 4 chords for Sidewinder Blues are actually 5 beats long. So, they start on beat one and then finish on beat one of the next bar.
Ie when playing those riffs you could count 1,2,3,4,1 .. then you rest for three beats 2,3,4 before moving to the next riff.
Thus, each riff can only be played once, every 2 bars.
Hope that helps mate!