In the Handbook of Model Rocketry, Harry Stine talked about 4 stage rockets, mostly saying they were unreliable and did not go any higher than a 3 stage rocket. He did not say, but I bet he built and flew a couple just to verify that.

I had one by using a F100/C5/C5/C6-7. Once. never found the two upper stages. And it was expensive to use.