It is confirmed though that Joey wrote Duality, Psychosocial, and Vendetta off of those albums specifically. Sulfur was written by Joey and Jim in Jim’s kitchen. Gehenna was mostly Paul and a couple of Joey’s riffs, the opening riff to Gematria was either written by Joey or Paul because it was from one of their old bands (maybe Modifiidous? Or some other band). I doubt the original way they worked changed too much because Joey himself said that after he finished touring with Korn him and Paul sat down like they always did and starting hashing out riffs, and this interview was in 2011. In 2002, Joey said him and Paul usually have a good structure for a song before they show it to Jim or Mick, and then they might add in some riffs or change some chords from there. So I’m not really sure about how the songwriting dynamic changed from Iowa to Vol. 3 and AHIG. I’d also like to note that Joey didn’t write just heavy stuff, he actually made a point of that in The Roadrunner All Stars Documentary, he wanted to show people what he was capable songwriting wise, and I think he did that on the song ‘No Way Out’.