Non-12 Bar for Vocals = Option of 12 Bar for Solo

Though the 12 Bat Blues Progression is the most common chord progression we play over, other chord progressions do exist. Some have very simple changes that can be "felt" and little to no study is needed. Some progressions introduce new chords and have unintuitive form lengths and require many hours of work in the practice room before ideas begin to flow.

Something always to keep in mind is that the chord progression for the vocals doesn't have to be the chord progression for the solos. In fact, it's a pretty common thing to do, historically speaking.

So, the next time you come across a progression that's difficult to shine on due to its unfamiliar chord progression, change the solos to 12 Bar and you're golden!

P.S., don't use this an excuse to never play to a non-12 Bar progression, you'll be missing out in all of the cool possibilities other chord progressions have to offer.