The Canadian health authority has listed the question "Does every individual container of a raw material need to be sampled for identification (ID) purposes" in their section "Good Manufacturing Practices (GMP) Questions and Answers" and answered it as follows:
For human medicines, each container of a batch of starting material must be tested for the identity of its content. Therefore, each container of each starting material, including excipients and active pharmaceutical ingredients (APIs), must be opened and sampled. After that, two options are possible:
1. Each sample is tested for identity by a discriminatory method (it is not necessary to perform all ID tests in compliance with the specifications, e.g. as per USP, but the ID test must be specific).
2. If a starting material is tested for potency, the second option is to mix and merge individual samples from each container into a composite sample. However, not more than ten individual samples should be used in a composite sample. A specific ID test must be performed for each composite sample; a content determination is also to be executed.
At the end of the question, a practical example on how the sampling of 72 containers of the same batch of starting material should be performed is included.
The complete question as well as its answer can be found in the Health Canada's Good Manufacturing Practices (GMP) Questions and Answers under Raw Material Testing - C.02.009 & C.02.010.
Strictly speaking, these requirements only apply for the Canadian market. Nevertheless, these regulations may be viewed as state of the art recommendations worldwide.