Yeah it's kind of sad that it only acknowledges the highest stat. It probably makes sense for balancing purposes but it super disincentivises actually learning any of your knowledge stats and sort of pushes you into picking the same candidates each run for their stats.
I wish there was a system of the lowest stat applies 1/2 rounded down to nearest multiple of 5 for example to the highest stat. Because it feels pointless to aim for like graduate or grandmaster on most of your knowledge stats because it takes too much effort and you waste many turns before a reward.