I was involved in a conversation where this guy was telling me that Zakk does too much "squealing" (aka, pinch harmonics). I tried to reason with the guy and tried to explain to him that it's just something he does. He's always been known for it. To me, it's the trademark that he's known for, just as Eddie Van Halen is known for tapping. It's most likely going to end up somewhere on every song, it just is what it is.. lol
How man actual albums is Zakk on? That's not an easy chore to figure out, but I'll do my best...
There's 12 Black Label Society albums (1 that's a "best of" that I don't really count) Of the 12, one is a live with a bonus cd of just covers
There's 8 Ozzy albums, 2 of which are live
There's the Book of Shadows he did way back when
Pride and Glory (that's a double album, if that matters)
He's done work on Damageplan's CD, not 100% if he did any guitar work, but he did backing vocals on Soul Bleed
Then there's all the little solo stuff he's contributed over the years, Fozzy, Blackfoot, Derek Sherinian (like 4 or 5 of his CD's), My Darkest Day, Rippingtons, Dope, Merry Axemas 2 (Christmas compulation), Black Veil Brides....
I'm sure that I've missed stuff and probably could've googled it, but there's no fun in that!
Hope that I've helped out..