Clinical perspective, offered as context rather than as advice. The version of this that has an answer is narrower than the version being asked. Narrow it and it becomes tractable; leave it broad and the thread will produce nine confident and incompatible replies.

Worth separating that from cross-border ordering, which this thread keeps folding into the same question. They behave differently and the advice does not transfer.

PeptideChemSF said:

The version of this that has an answer is narrower than the version being asked.

Mine went the same way, slower. Posting only so the count is not one.

PeptideChemSF said:

The version of this that has an answer is narrower than the version being asked.

Adding the part of the answer the thread has not reached. Start from the measurement rather than the conclusion. Almost every disagreement here turns out to be two people measuring different things and comparing the numbers anyway.

One concrete data point for the thread. One habit that pays for itself: post the method alongside the number. A figure without its method cannot be checked, and an unchecked figure is how this community accumulates folklore.

If somebody has the primary source to hand I would rather cite it than paraphrase it.

OP back with an update, since a thread like this is useless without one.

For the archive: it took about six weeks rather than the two I expected, and the difference between those two numbers was the whole of my problem.