For the record, I'm not wrong either.
Interesting... could it be that we're all right, and that, depending on the way it's notated, 5:4 designates EITHER a polyrhythm OR an odd grouping? Afterall, you guys aren't looking at what I'm looking at. The freaking 5:4 is NOT going over the entire freaking measure, it's going over the freaking 5-note group of 16ths. freaking... freaking....
OK, I'm losing it. But I'm right dammit! I'm right! At least I'm right according to the lessons I've learned from DA MAN!
Okay ... this is NOT what I feel that you are saying in your earlier posts. That is called PHRASING. When you say 5-note group, that sounds like quintuplet, which you did not refute.
So what you are saying is that is that you are actually playing is 5:4 phrasings or groups of 4 sixteenth notes, phrased in 5? If so, there's a big difference. Sorry to be picky, but we have to get our terms right since we can't see what you are talking about.
Here are 4 groups of Quintuplets, which is not a polyrhythm.

Here is an example of 5:4 in which quintuplets are being played with accents on every 4th note, which creates a 5:4 polyrhythm between the accented notes and the kick drum.

In this example, there is a 4/4 filled with sixteenth-notes. Here you can see that accents have been placed every fifth note to imply a phrasing in 5. The label of 5:4 is
NOT correct in this example. It should just have the bracket with a
5.

Lastly, an example of 5:4 used correctly. The 5:4 tells the performer that the 5 quarters notes are to be played in the span of 4 quarters in 4/4 time.

Do any of these examples look like what you are seeing in Chafee's book? Unfortunately, I don't have the books, but I should.

I know we got way off from your original post, but if something can be described as
5:4, it should be for polyrhythms or to show that there are too many notes in a bar and that they should be played in the span of the second number; five notes being played in the time that you would normally play 4 notes of the same note value.