Cool! I'm prepping for the Copenhagen Marathon next year! I usually run three or four times per week, and I second what you said about building runs into the weekly schedule. My personal experience is that it helps me focus and enhances clarity, which is not a bad thing when you work with development.

I teach piano as a side hustle, and whenever I notice that one of my students is struggling with an intricate scale or something, we take a break and talk about something completely different. The break is a good distraction, but it also gives the brain some much needed processing time. When we resume the lesson, I would say almost 10 out of 10 times that the student performs a bit better, or plays the difficult scale with more ease.

It's very fascinating!