rachel_ABQ said:

Most of what circulates confidently in this community traces back to one summary of one study, and the qualifier was dropped somewhere in the third…

Adding the part of the answer the thread has not reached. Take it one variable at a time. Almost every unanswerable question in these threads is unanswerable because three things changed in the same fortnight, and no amount of subsequent argument can untangle them after the fact.

The figures, for anyone assembling their own picture. Practical: whatever you change, write down the date and the reason. In three months the reason is what you will have forgotten, and the reason is what makes the record worth having.

A narrower follow-up, since the general answer is now clear:

What actually distinguishes 503A from 503B, in terms of what each may make and from what starting material?

anders_CPH said:

Practical: whatever you change, write down the date and the reason.

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.

anders_CPH said:

Practical: whatever you change, write down the date and the reason.

Agreed, and one caution: a single measurement is not a measurement. Anything that moves day to day needs a trend before it means anything at all.

Worth separating that from compounded supply, which this thread keeps folding into the same question. They behave differently and the advice does not transfer.