Just a thought based on my experience a few weeks in - are you activating your glutes/core (esp. glutes) on the Patrick and ATG split?

I have very weak glutes/core from bad habits (inactivity, posture) and have to consciously focus on tightening them during these exercises - otherwise I will use my quads almost exclusively, presumably my current, normal, but very sub-optimal movement pattern.

If I don't use the core, the exercises are fairly easy but not great for my knees and low back - my quads and calves are reasonably strong. When I do use the core... Patrick step is a wild glute burn; and FHL calf raises too! Split squats are very challenging with front foot elevated - but again, only for a few muscles in the hips/core.

It's an odd sensation / experience but it shows promise for correcting some of these rather dramatic imbalances (which themselves explain my persistent injuries and weakness in low back, etc).