This is garbage, and shows no actual knowledge of the way these so called "coins" were made.
We are talking medieval technology, in the 1500s, and they had no roller press to roll out sheets, and no stamps to press out the blanks, so this absurd notion that they made "coins" and the cut them up, is ridiculous.
What they actually did, was to pour the silver into long thin bars, that were then hammered flat.
They then cut these flat bars into rough squares, called a planchet, that were then weighed, and if necessary, trimmed to the correct weight, by making adjustment cuts in the corners until the planchet was of the correct weight standard.
This would result in a 4 sided planchet, with the four corners trimmed, to produce an 8 side "COB", which is were the term "pieces of eight" comes from.
It has nothing to do with the value, as the cobs were made in a variety of denominations, all having the same eight sides.
https://mexicannumismatics.com/history/cobs/cob-coinage