If you have any understanding about how math works, you would know that whether or not the relationship is non-linear, there is a relationship and that relationship can be tested. You are simply refusing to do work that, at worst, would give you a reasonable approximation if not the exact answer.If the modifiers in question cause a non-linear change in TH proc rate, then the test you are suggesting is a complete waste of time.
It's a big "if" in the first place, but even if your conclusion isn't accurate, it is not a "complete waste of time." The very worst thing that can happen is you find that the data you collected isn't useful which would prove your "what if" is the case. This would save anyone else the time spent testing it and would also point future people exploring this in the right direction. Testing things is NEVER a waste of time.
If I had any reason to believe that there is some super secret hidden complexity to how procs work, I would test for it. But I have no reason to do so because neither you nor anyone else has brought forth any evidence to suggest that this might be the case. All you have is a theory that's based on nothing but an argument you had with someone.
I can't tell you what to do with your time. I'm merely suggesting you actually do something about your alleged problem rather than wait for an answer that will never come, as you by your own admission claim to have been waiting a decade, and you will likely go to your grave not having the answer to this incredibly trivial issue of how to optimize proc rate. You will probably get all the drops you're optimizing for in the time it takes you to get an answer without testing. But hey, you do you. I'd love to help you find the answer, but you have to want to find it. And I mean that, if you want to explore it, I will be supportive of that. But you have to stop dismissing me out of hand.