If you’ve tried primarily higher volume and high intensity style training (multiple sets to/near failure) for them, and gotten lackluster results, consider giving high frequency, low intensity (no failure/maybe 1 set) a shot. Especially if drugs are in the equation, hitting them upwards of 5x per week is totally doable. Still train like normal with the slow, controlled motion, but always have multiple clean reps in the tank. Something along the lines of 3-4 sets 5x/week and 1 set for each muscle group being to failure each week.
Another option is a similar high frequency approach, but with low volume and high intensity. Something like 1-2 sets 5x/week and all of them to failure.
No matter how tried-and-true volume and intensity may be, in the same way that some people don’t get energized from caffeine, you could be one of those who has arms that need to be trained in a less conventional way to yield optimal results for your body.
As another user above said, those with good arm genetics are those who tend to have good/big arms, and when you have good genetics for a certain body part you really don’t need to concern yourself with how you train them. On the flip side, somebody with poor arm genetics really needs to evaluate all variables to optimize what limited growth they can muster.