Moderator note: good thread. Keeping it here rather than moving it, because the question is general enough to be useful.

RegAffairsDC said:

Update: the thing I was blaming turned out not to be the cause.

Same pattern here, and in the same order.

RegAffairsDC said:

Update: the thing I was blaming turned out not to be the cause.

Adding the part of the answer the thread has not reached. Whatever the answer turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, and invite the correction. That is slower than asserting, and it is the only version that survives being wrong.

One concrete data point for the thread. If you are comparing against somebody else’s result, check that you are comparing the same measurement taken the same way. Most of the apparent contradictions in these threads dissolve at that step.

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

How long did you give it before you decided it was working?