You’re wise to consider this, because this can be a thing. As @anon61582445 said, it depends on your physical constitution as well as the robustness of your energy systems and even the different conditions you’re wanting to treat. Because of the point you’re wisely considering, the Official Sapienmed FAQ (Updated) offers a guideline that we refrain (at least, in the beginning, as we’re getting familiar with ourselves and with fields, etc.) from using more than 4 fields which are creating permanent physical changes for ourselves. For the beginner, exceeding that guideline might be more than they can manage, which could then slow down the improvements they’re wanting to see. Of course, as they heal, repair, restore and expand their energy systems (as well as their physical bodies) it is probable that they could be able to manage more than the recommended guideline.
Keep in mind that Sapien have given us a number of powerful–what I would call “universal”–healing fields (for example, New Release - Advanced Healing +Voltage Repair or The Shamanic Medicine Blend as well as others). We can use these fields to treat several conditions at once so that we can have the healings we want without overtaxing ourselves.
The nice thing about these fields is that, when we have several conditions in need of treatment, those conditions often can be “symptoms” of a not-obvious problem. Many of Sapien’s ‘universal’ healing fields can treat both these “symptom” conditions as well as the not-obvious, root problem. When the root problem is taken care of, we might not need the several specific fields we were wanting to play. And some of these ‘universal’ healing fields can even address emotional or energetic root problems for us.