AMEN to that, bro. I have been more or less working with Russian longer than anyone here (first Russian class was in high school, 195, and I still have problems with motion verbs.

I would simplify the categories, however, into a binary opposition:
unidirectional verbs and
all others. (i.e., verbs that are not specifically unidirectional).

If you're talking about a verb that means moving in one direction only one time, then use the идти/ехать/лететь group, otherwise ходить/ездить/летать