Don't mean to flame or anything, just informing for the sake of better understanding - a few things to note:
Yates was one of the very few bodybuilders "on roids" who used HIT style training, unlike most of his contemporaries who used very high volume training. It's good to ask - why did he not do the same as the others? For some time, Lee Haney, who used high volume training and also had excellent genetics was the top competitor for nearly a decade until Dorian Yates came along. Dorian really pushed the envelope on size/conditioning and dominated the scene for 6 years.
The usage of steroids cannot be THE influencing factor in training style (BOTH camps use it), especially as many say it's the other way around; that VOLUME training requires extreme 'assistance'.
IMO, Dorian was very intelligent with his training and questioned everything he did (if it didn't serve a purpose, he dropped it)...so it's not like he did it "just because" (accidently) or just followed everyone around him who did things because it was the norm (or blasted the muscles with everything, just incase)