The question in the title: What this community means by "a source", in practical terms I will give what I have already checked below so nobody repeats it.
Counting it rather than describing it, because the count is the part that can be argued with.
12 instances over 11 weeks, recorded the same way each time, 3 of them different enough from the rest that I have set them aside and said so.
That is the whole dataset. The question in the title is what it does and does not support.