Well, I still have older CD-r stock around, some 16x and some 32x that I will burn two speeds down (16x at 8x and 32x at 24x), but once I get to my TY CD-R, I’ll burn those at the 48x, because I’ve read here they will “accept” the 48x with no problem. I want to name some names of CDFreaks that stated the same thing, but the problem is, I can’t remember them right now. 
I was told at 3 different shops that when the 16x-24x CD-r stock was around that I should burn it two speeds lower for “a deeper burn,” ca. 2001-2002. I can also understand that preference for audio, since it used to be on older cd-r stock (IIRC) that one could sometimes get skipping in the songs if one burned too fast and didn’t slow up, because it was older media. I’ve had that happen to me on older media, too