"Don't write 10-minute-long songs [for Slayer]. [Laughs]
"I think that's the first thing. I tend to sometimes, in the Exodus realm, wander into some very progressive territory. And that's cool - it's all thrash metal to me.
"I think the biggest difference between one band and the other and the next band after that is quite often just note selection.
"Slayer - a lot of riffs are very chromatic, and it's as simple as adjusting your style from one to the other, which, I think, after six-plus years in the band, I definitely have as good an insight as anybody into how Slayer writes a song, since I can play such a large amount of the catalog.
"So, yeah, when that time comes and we are ready for the next album, if Kerry wants me to contribute, I've got riffs. I've got stuff right now that I've written that I am not using for Exodus, because it was kind of maybe just unintentional subconscious thing, like, 'It sounds a little too Slayer.'
"So I pushed that aside, 'cause I spend predominantly the bulk of my time playing in Slayer nowadays. I've gotta make sure not to cross-contaminate. I've gotta treat both bands like a crime scene, you know."
Asked whether being in Slayer for six years already feels "surreal," Gary replied:
"I don't know that any of it does. I think it's probably a little more surreal nowadays. And, I mean, it really sounds odd for me to say it, but it's a little more surreal when I get a rare chance to go back and do Exodus shows. [Laughs]
"'Cause those guys are my brothers for most of my life, and the Slayer guys are my brothers too. I'm fortunate to be in a position where I have two bands that I call family. It's kind of like just second nature.
"And then, when I do get the chance to do some Exodus shows, it's, like, I've been away for a while. So it kind of, like... I've gotta remember that this is the band that I've been in since I was 17 years old."