That is a a very interesting question Lonnie. I agree, Elvis seamed really in to it as far as the music he wanted to perform during this time, and I don't recall (to my knowledge) him ever rehearsing any more after this?
Maybe he was beginning to over come the divorce that had occurred late during the previous year, and so he dove in to his music again hoping to find some sort of peace?
What really disappoints me is that he gave in to the fans and went back to the same old song routine after the August opening night in Vegas. Had he continued his show playing different / rare songs I think he would have fealt better, and he might have possibly laid the ground work for even bigger projects later on.