nasser did so few reps with 225 mostly because his shoulders are all kinds of fucked up these days. synthol and the surgeries to drain it has destroyed his muscle, he probably can hardly move his arms these days.
flex photoshoots weren't always with fake weights. look at them years ago, the mid/late 1990s come to mind. i have an article sitting around showing a chest workout with cutler. there's one picture of him holding 405 at the top on incline, but the only picture of him with the bar at his chest is with 225. there's also a shot of him at the beginning trying to incline the 200 pound dumbbells and failing, complete with three spotters panicking trying to help. the weights were obviously real.
i would hazard a guess that the fake weights started when injuries started happening, especially when fux got crushed. it's only been in recent years that all the pros have been using gigantic weights for everything.
