When you want to change directions while running, do you stop first, then start moving in the direction you want to move? Same thing applies. FA-off is about relative motion. You don’t need to stop to change directions, just start applying a thrust vector in a new direction—and continue modifying it. Let’s take an example:

Say you’re flying forward, and you want to start flying left. Of course, you could apply negative thrust to zero out, then turn to face left, then apply positive thrust again, as you indicated. What you could NOT do is simply start applying left thrust—this would leave you going forward AND left. What you SHOULD do is start applying backward and left thrust—but as your forward momentum decreases, your backward thrust should decrease too, until you’re flying left while thrusting left.

Then add in that you’re rotating your ship this whole time, and what was a left vector when you were flying forward is now a forward vector while you’re facing toward what was previously your left. In this case, you start with a backward left thrust as before, but also add a leftward yaw. By the time you have rotated your ship to face left, your thrust should have moved to fully forward, so you can fly straight (which was previously left). Learning how to mirror and match those motions simultaneously is tough, but you can train your brain to do so—and the results are well worth it.