Just imagine a textbook that gives you the understanding you need to score high in math competitions…and it describes less than 1,000 problems. This in itself is a major discovery in metacognition.
I'm not knocking the work. They report large improvements using relatively little data. That's good. But let's be clear that this is further training of a good sized LLM that has read far, far more than any human that ever lived already.
Most of the math competitions people are working on are high school math competitions - these have problems from a relatively small set of mathematics, so that high school students can reasonably know the appropriate background.