I started tracking deep-focus blocks and run frequency in the same weekly sheet. The pattern is not perfect, but it is consistent enough: easy runs correlate with better concentration the next day.
I do not think running magically improves intelligence. It does improve stress tolerance and mental rhythm, which matters when working through stubborn problems.
My current policy is low drama: run 3 times a week, keep most runs easy, and protect sleep first.
Anjou Zhao 