@jonny @spacyoddity welp, yeah, the "targets" are not always consistently "motor"/production/articulatory targets, either, because THE GOAL IS COMMUNICATION
We already know that there is widespread diversity in AmE articulator production of syllable initial /r/ for example (with at least two modes of tongue shape, retroflex and apical bunching) but nobody seems to care about those differences so there is a lot of inter-speaker variation.