Originally posted by chris mood
Form and rhythm are 2 seperate things.

I know that. But not all songs have the same form either, let alone a certain genre of music has to fit a certain mold or "form". Granted a traditional or more common blues song will fit the mold you presented but it is also possible to do anything. I wouldn't have brought it up since this is alittle off topic, but you said if a form is not a certain way it's not a blues song. I don't understand.

4 3 bar patterns? What would the chord progression be?

Anything. The harmony could be anything as long as it's interesting and it is a nice compliment to the melody. Although it may seem daring, it is perfectly fine to try to find new progressions that are not in the list of top 10 blues chord progressions (form).

You may say well then it aint blues anymore, but since when should anything stay strictly traditional in this sense. Especially something that is expressive as music. Blues to me isn't a form like "sonata" or "rondo". Blues to me is more about the way of playing with certain rhythm patterns and melodic line/harmony that are associated with what we know as blues. The way music continues has infinite possibilities. Breaking these formal rules can make the song more interesting, I mean who wants to hear the same dinstiction in every single song. And yes it can still be blues.