A lot of the focus here seems to be on the military utility, which is also how I suppose the separation feature was presented in the show.

But an obvious use case would probably have been less dramatic. Anytime two things needed to be done at the same time. Send the drive section to the more distant or dangerous location and keep the saucer where it’s safer, like running supplies or something for a planet.

Don’t know it would have been good TV though?! Perhaps if it was used as a plot device to put the ship in trouble?

But in contrast, this lawyer (Neera) won by mainly by being a good lawyer (albeit in a tv legal drama kind of way). Setting things on fire with the first witness to create a bunch of fog and doubt about the premise of the case, realising that other important regulations impinge on the case and setting up testimony to substantiate the effect of those regulations.

My memory of most other officer-lawyers is that their methods tend to focus more on the moral "issyew" (Picard's pronunciation of "issue" in Measure of a Man).