Suppose that a for a given -CH2-, there is coupling to two nonequivalent H nuclei with two different coupling constants, we would observe a doublet of doublets. The same reasoning can be applied to more nuclei. Let us now assume that for carbon-2 of 1-propanol that there are two distinct coupling constants, to the hydrogen nuclei on C-1 and C-3. One should ideally see a quartet of triplets or a triplet of quartets (not a triplet of doublets or a doublet of triplets). However, it seems plausible that many of the lines will overlap, but in a way that depends on the relative sizes of the two coupling constants. If the coupling constants were identical, then one should see a sextet.