Data-Driven Approach to Gym Workout Efficiency

I’ve been mulling over how to apply data science principles to my workout routine, and I’m curious what others think. Specifically, if we wanted to compare the effectiveness of a structured leg day versus a more flexible cheat day, could A/B testing give us meaningful insights? I’m wondering how you’d set up variables like recovery time, energy levels, or strength gains to track over a few weeks. Has anyone experimented with this kind of approach, or do you have suggestions for making it practical without overcomplicating things?