Something you could say generally about phrasing is that it expresses an ownership of time: good players and singers proceed in their own good time and aren’t merely hustled along by the programmed “good time” of the song’s beat that everyone counts on. They won’t be held back and they won’t be rushed.
Perhaps they want to put their own good time into a clear shape, making us wait with them for a whole measure. But then it’s no longer a “phrasing” effect, it’s a structural modification of the verse or chorus.
That’s what happens in “Rock ‘N’ Roll Doctor” at 0:47, 2:17, and 2:25. Chugging along for an extra measure just for the hell of it is a change of song structure so obvious, so gettable, that we want to let it count as our own take-a-break prerogative. It’s a full-service rest stop in the middle of the song highway. It’s Everyman’s ownership of time.
Once the unmistakable extra measure has sent its message, you can appreciate that “Rock ‘N’ Roll Doctor” is shot through with smaller intervals for gathering yourself, cleared-out beats at :08, :11, :22, :39, :45, :53, 1:19 and so on. Typically, Little Feat is colluding with the audience on showing the song who’s boss.
Yet the song itself (and this seems a contradiction) never loses a smidgen of forward progress, for the band keeps it absolutely taut. I love watching Richie Hayward’s drumming in live performance, lest I forget how wound-up the song is:
 It’s so common in blues songs that it can register as part of the structure rather than a modification.