I personally have known Gajda for decades, he was totally natural and the reason he "retired" was he couldn't hold off the roid guys any longer.
To have beaten Arnold Schwarzenegger and Sergio Oliva, I'd have to guess he was an "natural" as they were, whatever he may have told you notwithstanding.
If it were the most effective way, the guys taking God knows what PEDs would all be training HIT style, right?
Not necessarily. People, especially men, define themselves by what they do. If a guy is a bodybuilder, he'll fill up his time with bodybuilding "stuff." Because that's who he
is. While I agree that sport-specific training requires a fair amount of training time, strength training arguably does not. In fact, too much is counterproductive for purposes of strength and hypertrophy. But guys on steroids can get away with a lot of mistakes that they otherwise couldn't.
Most people who recommend 3 sets do so either because someone else told them to or because of "research" that often cites a 1962 poorly conducted and poorly interpreted study by Richard Berger. Here is an assessment of that study:
http://bjsm.bmj.com/content/36/5/319.full
Please read the piece and then consider the cross referencing by "experts" who recommend multiple sets, relying either directly or indirectly on Berger's study:
Fascinating, isn't it? I've posted this link in the past but I thought I'd do so again because it bears repeating.
The difference in outcome that Berger cited from doing 3 sets instead of one is about a 3% improvement. Are you willing to do 300% more work for an incremental ~3% improvement, if that? I'm not. And even if you were, and went all out, which one of us would tax our recuperative ability first, all else being equal? But the bottom line, as I see it, is this: you can pay $10,000 for a $10,000 car, or you can pay $30,000 for a $10,300 car. Choice is yours.