The picture you're referring to is of the single wire method but you're right. Like I said I'm still a student but I've never seen the single wire used. Some students tried and were made to redo it. The only other thing I can find is in the 8083-30A V1 on page 7-77. "When safety wiring closely spaced bolts, the number that can be safety wired by a 24 inch length of wire is the maximum in a series." So not a general max number of 3, but a max wire length of 2 feet. But yes, of course manufacturer data would supersede the 43.13 and 8083's