been listening to a series of podcasts about the DISC model of behavior. it's bullshit, full of stereotypes, and even if it measures accurately, it literally only tells you about two dimensions of a person's behavior*, but there are at least a couple ways it's useful anyway. If you're dealing with people who actually have these stereotypes in their head and use them as communication tools, you can probably switch them over to more useful ways of communicating, depending on the situation. Second, if you're not use to thinking about how other people communicate and are motivated differently from yourself, DISC is decent crutch to get further along in that direction.
* Thinking about this geometrically, I think there's also a property of the "points" in this 2d space that they aren't describable in two dimensions because the DISC "point" is really a shadow of a higher dimensional behavioral description.
(I think of a point as a description of a person's behavior over a certain time span)