Do composers like Bach, Beethoven, Mozart, etc... generally have some logic in motivic motion? When they sequence or use motives in "creative" ways is there some reasoning to choose the interval the motive is played at? Is it strictly choosing a chord tone that works or do they use some larger feature? e.g., playing the motive on an interval that works harmonically(a transpose the interval between the motive's original tonic and the chord it is presented on) or choosing it based on other reasons?
Beethoven's 5th is a good example. He chose to play it a M2nd down. Obviously in that case it is probably somewhat arbitrary... But it obviously effects totally different outcome if the intervals were changed IF he used that fact.
But even if not, what about the motives that follow? They are sequenced in a more complex manner. Obviously the whole piece is built off such things and the ways the tones of motives were chosen wasn't willy nilly.