This agreement becomes to governing factor. Whether a Yes or a No answer is most desirable depends on what we ask for, but most often we will ask in such a way that a strong response is good. If it is weak, we could then work on the issue of feeling good about oneself, with our usual processing techniques. And then, when we appear to have gotten somewhere, we could do a muscle test again to confirm it. If it is now strong when we ask the same question, then we have probably done a good job.
Muscle testing is a very finite way of testing.
If nothing else, it appears very finite to the client. The client can much more easily invalidate purely mental and emotional results. But if we have tested it and we both realized that what used to be weak is now strong, that might weigh a lot more heavily in the favor of accepting the change that took place. The muscles really do react to what one thinks and feels and imagines. But the test it fairly honest and unbiased.