Break in oils, zinc and all that jazz

No situation in particular...I was just reading the thread about the cam bearings that went bad on the 340 and other various threads about zinc additives and flattened cams and what not....It got me to thinking about different engines I've worked on...Typically newer stuff but never heard of needing zinc in those engines ( without roller cams) and having a cam go flat but have heard/seen pics of the failures of cams in various V8's.....I've never gone as far as to see what spring pressures Nissan run...