explanation for Q21 was lacking for me - as I'm sure few others also picked (A) "continuous sound" thinking it was mentioned in Passage B. It's important to understand how the LSAT writers tricked us into thinking it was mentioned in the second passage when it wasn't, not brush it off as "it was simply never mentioned."

Here's the explanation I came up with instead: Passage B may have been confusing for those of us who picked (A), because it states music listeners experience positive emotions when their musical expectations match the actual course of the music. I personally got this wrong because I equated "continuous sound" to "match in expectations," but there is a nuanced (albeit very clear) difference between the two. For example, just because you successfully predicted what was going to happen in the song, doesn't mean it was a continuous sound.

it's less about the course and more about the application. if you're just starting out, save yourself the trouble and push your test date. unless you're already scoring in the mid 160s, in which case you probably don't need the course.

Besides what others have already mentioned, I want to reaffirm the importance of building stamina. In reality there is a notable difference in taking 3 sections vs 4. The more you get used to taking the latter, the better you would be prepared for the actual exam.