There’s no harm in taking a variety of subject tests. You should take one of the practice tests to get an idea of how you would do as grades and scores are not always correlated.
My older son - planning to major in CS took Math 2, Physics and US history (pretty easy if you are taking APUSH concurrently) He had excellent grades and excellent scores. No surprises there.
Younger son - planning to major in International Relations took Math 2 and got rather a low score, Biology (E) and got a 720 (He had an A or A- in AP bio), and US History 790 (He had an A in the course). Since he didn’t like his math score (and should have known not to take it as he hadn’t done well on any practice test), he took the tests again the following month. He too Biology (M) got the exact same score, US History also the exact same score and a 710 in Literature having never gotten better than a B+ in honors level English courses.