Adding the clinical framing, because it changes how the question reads. The useful move here is to separate what is established from what is widely repeated. Those two sets overlap less than the confident tone of most write-ups suggests, and the second set is where nearly all the disagreement on this board comes from.

Ask again with the specifics and you will get a better answer than this one.

SarahChen_PharmD said:

The useful move here is to separate what is established from what is widely repeated.

I am going to disagree with the direction of travel here. The thread has converged on the tidiest answer rather than the best-supported one, and those are not the same thing.

SarahChen_PharmD said:

The useful move here is to separate what is established from what is widely repeated.

That is right, and it stops being right at the edges. The general case is well behaved; the interesting cases in this thread are all at the boundary where the general case breaks.

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

SarahChen_PharmD said:

The useful move here is to separate what is established from what is widely repeated.

Saving this. It is the first explanation that did not require me to already understand it. Sending this to two other people who asked me the same thing last week.

Moderator note: the sourcing question belongs in the vendor section and has been split out. Carry on.