As far as I can tell from reading the discussion section of the original paper, they unfortunately didn't address either a compounding effect or the fact that a

As far as I can tell from reading the discussion section of the original paper, they unfortunately didn't address either a compounding effect or the fact that a small difference could accumulate over time. With the caveat that I may be misinterpreting the table, they did show that students with higher initial knowledge had faster learning rates [0]. That seems to be consistent with some students gradually accumulating an edge that grows over time, even if prior knowledge due to having more opportunities is also a factor, which is the authors' hypothesis. However, those rates were in log odds, meaning they decreased over time in percentage terms. That's only within the same task, so I don't think that rules out other types of compounding. I will say that a student who consistently learns slightly faster and over the course of their entire education ends up drastically more skilled as a result would definitely be a faster learner, but that seems more muted than most people's intuitions of a "fast learner" or someone with a "knack" for a subject. [0]: https://www.pnas.org/doi/10.1073/pnas.2221311120#t02 https://www.pnas.org/doi/10.1073/pnas.2221311120#t02