I don't necessarily believe in the idea of "Learning to run fast on tired legs" I don't know if anybody really knows why things work, but when things are done enough, we find out if they can work.
Running 4-6 x 200 after a tempo is fine. I am a believer in training 5 paces, and a workout like this can help you keep contact with more paces, or what you might call more energy systems, within a period of time; while giving more recovery days in between.
It's something that's in my bag. I could go months without using it, but I've done cycles like this, and it can be safe and effective.