LW TBn

The turnaround (last six beats of the twelve bar blues in most cases with LW) are going to be your best examples. The end of the second chorus of "Rocker" is a good one to look at. There's no way to know for sure if he's tongue switching (for hole 1), but instructors like myself and Joe Filisko who do a lot of transcribing (intense listening) and have spent time with this material for many decades, get the impression that he is. 

P.S. whether to tongue switch or not is really not an important subject... hole 1 sounds good with standard TB, pucker or switch... we just believe that it sounds a tiny bit better to tongue switch. I personally do both... pucker the 1 most often, tongue switching with medium-tempo and slower songs (though doing it fast is not a problem, I just don't see the need to do it... if I thought it sounded a lot better, I'd be doing it). Also keep in mind that new students learn to play this way, so they use it for all tempos and they're good at it, since it's all they know. In the end, it's really splitting hairs... you decide what you want to do.