As we noted briefly above, the existence of a regular pattern of suffixation with n distinct suffixes will generally give rise to a large set of stems displaying all n suffixes, but it will also give rise in general to stems displaying most possible combinations of subsets of these suffixes.
if there is a regular paradigm in English consisting of the suffixes NULL, -s, -ing, and -ed, we expect to find stems appearing with most possible combinations of these suffixes as well.