Thanks for the reference to Yeivin's book,
about which I have heard, but do not have.
On the other hand, I do have about 50 books of and on the masora,
including several with extensive compilations
of various phenomena from the pre-computer days.
I assume that Yeivin's book (2003?) is the result
of computerized studies.
I believe that the reference to 5 appearances is specifically
refering to the word C)U.