Watch the Sweet 16 online guitar lesson by Chris Buono from Guitar Lab: Blues Progressions
Here's the first of many examples where a blues progression is more than just a set of 12 bars. Here we have 16 bars of shuffled glory in F# coming at you. If you've tried to play a blues outside the 12-bar count and had some trouble making it feel right--it's not you. The 12-bar blues is so deeply engrained in our rhythmic psyches it's hard to stray away from it. That's why this first taste of non-12-bars is basically a 12-bar blues with bars 9 and 10 tagged two times before resolving to the I7 (F#7). Part of what makes this all flow is the inclusion of the IV chord that follows the V in bars 10, 12 and 14.
Notice the chords are played on the top four strings in all three instances. This string set choice enables you to effectively cut through the mix in high-tempo environments such as this.
Working through this 16-bar blues will start to get you in the right groove for the various progressions that will have non-12 counts. When playing a blues that's not seated in the time-honored 12-bar count the most important aspect is to key in on making the pocket come to life because when the flow is real so will be anything you play.