Testing what is actually in it
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There is no way to know what is in a blend by looking at it, and in a category where the label is a quantitative claim, that matters more than in most.
Three different questions
Identity. Is this material what it says it is. The requirement 21 CFR 111 is most insistent about and the one most often skipped.
Potency. How much of the active is present. This is what your label claim asserts.
Purity and safety. Heavy metals, microbial counts, and contaminants relevant to the material. Botanicals in particular carry these risks.
They are separate tests, frequently confused, and a certificate covering one says nothing about the others.
What to test and when
On qualification of a new supplier or material: the full panel, because that is when you decide whether to trust them at all.
On incoming lots: identity at minimum, on a defined schedule, with a written justification for whatever verification approach you use.
On finished product: potency for the first batch of any formula, and periodically afterwards, plus whenever anything in the formula, the supplier or the process changes.
Reading a certificate of analysis
Check that it names your lot rather than a generic specification. Check the test method, because methods differ in what they detect. Check the date. And check that it tests what you care about rather than what was convenient.
A certificate that says "conforms to specification" without numbers is a statement of opinion.
What a small brand can realistically do
Not everything, and the rule does not require testing every attribute of every lot. It requires written specifications, a documented approach to verifying them, and records.
The workable version: full panels at supplier qualification, identity on incoming lots, finished potency on first batches and on change, and a written program explaining the schedule. That is defensible, affordable, and considerably more than most small brands in this category actually do.