Aside from such special cases as a group of tonally different vowels, the analysis into unit-length components is of interest to linguists only when it is carried out for all the phonemes of a language. Only then can the components be so selected as to yield the simplest set of new elements identifying and supplanting the phonemes.
- Harris (1951), a pag.146

[…] the unit-length component analysis of a whole language differs in purpose, procedure, and result from the analysis into long components. Combinations of the two techniques may be possible in some languages, if it is desired to set up elements which can express both the distributional limitations […] and the speech feature characteristics […]. In any case, when an analysis into unit-length components is carried out, it is desirable to do so on segments from which the greatest possible number of restrictions on occurrence have already been removed […].
- Harris (1951), a pag.149