puzzle solved

Thanks to the wisdom of those with much more clothing-related experience:

HannaUNC1 (9:53:24 AM): the purpose of the permanent press cycle on the dryer is to dry permanent press fabrics at the ideal temperature so that they do not wrinkle.
HannaUNC1 (9:53:59 AM): the point of a permanent press shirt, as opposed to a 100% cotton one, is that the latter will wrinkle and the former will come out of the permanent press cycle all nice and fluffy and unwrinkled without you having to lift an iron
HannaUNC1 (9:54:18 AM): the same principle works for fabrics that are part synthetic
HannaUNC1 (9:54:56 AM): but you are accurate in saying that you should be careful what you put in there, because it is a hot enough dryer cycle that it can shrink jeans, for example, and lord knows jeans aren't long enough already.
HannaUNC1 (9:55:11 AM): things you don't want to shrink, you should wash in cold water and dry on "delicate"