The following Think Sheet are some of my notes and interpretations of the Design Thinking Process and the 7 Windows of Instructional Design. This is a great example where cross study in multiple fields can provide insights and new mental models to consider. I find the mental exercise of studying something unrelated to fencing and finding ways to apply/interpret those theories into fencing fascinating and worthwhile.
Another recent example, is when I challenge Renald and Ladrona to study Fencing through the lens of Dungeons & Dragons. Their goal was to consider how principles and ideas in D&D can provide a new perspective into many aspects of fencing (which they found, by the way).
Even if a study into an unrelated, or even slightly related, subject does not prove to be immediately applicable, the experience of deepening your mental well is always worth it.