From memory he was pretty close to Kerry Kayes who was as scientific as anyone with his approach at the time. Not that Dorian had anything secretive or the others didn't have , he just worked out what worked for him and stuck with it, similar to his whole approach to the sport, he trialled different things and wrote everything down. Genetics and drive were the determining factors in his success along with the required drug use. But there were plenty of guys using a hell of a lot more and didn't look like Yates, to this day his 93 shape hasn't been equalled by himself or anyone else after.
Yes Kerry played his part as did a couple of others
Especially on the PEDs He Used.
As you stated though Dorian was very Self Driven / Strict / Hard working
And had a Sensible approach to his training/ diet/ Drugs/ Rest
Plus Very Good Genetics.
He wasn’t that big a user - Certainly not anywhere near some of the Ridiculous
Drug protocols that are posted or spoken about.
His original Temple Gym was about as hardcore spit & sawdust as you could get.