How sheets of notes are graded?

I sent in a couple strips of fractional notes recently, one graded higher than the other. Thoughts on why?
This one graded XF40:
This one graded AU55:
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I sent in a couple strips of fractional notes recently, one graded higher than the other. Thoughts on why?
This one graded XF40:
This one graded AU55:
Comments
I’m guessing here, but believe they use the same guidelines as when they’re grading an individual note. They look for folds, handling marks, annotations, pinholes, stains and check how well the notes are centered on the sheet. They probably also try to determine if the sheet has been washed and/or pressed.
Also was thinking of the conundrum of one note being Unc. and another note being lower grade. Obviously they have to default to the lowest graded note.
They seem to be looking at the XF as quarterfolded (3 folds) and the AU as having a single fold between two of the notes.
Notes with three folds usually grade XF while those with a single fold grade AU.
They grade a block or strip as if it were a single note.
Now do margins folds count on sheets with wide margins and if they do, why not trim them off? Should that affect grade?