Yes, you are within the rule-of-thumb that’s advised for the world at large, yes.
How do YOU feel with your fields? That’s the real question, and only you can answer that for yourself.
I don’t know that I would come to that same conclusion. You’re still asking your body to make permanent physical changes and that’s the piece that’s “taxing” to us. The fact that they’re all 4 synergistic might mean that you get your healing more completely or more thoroughly or sooner, so you can reduce these 4 to use other one instead.
Heck, going by the key question I asked you above, you might decide that you could handle more than 4 physical fields or more additional fields, no problem.