This is way too much faffing. First thing first I don't have these sort of machines in my gym which takes plate loading it's either dumbells and barbells or machine wt stacks with pins so you can't unload anything in the eccentric phase. It need to be put back on the stack before changing wt as we all know.
Also there are so many other advanced training techniques one can employ other then this without needing someone to stand right next to you during your whole set.
Also I have trained arms every way possible and the best pump and results are achived (imo) while training arms (bi , tris) as a one medium size muscle group. so I don't think they are two muscles they are one for me and I ALWAYS train them in superset fashion. Doing a straight bis exe and then resting and doing another and eating and so on is so boring for me. I tend to stack a heavy duty move with a not too taxing move so for ex barbell curls with reverse push downs for recipes , close grip smith bench with preacher curls. rest only when I need to.
I really believe if you train this method your body gets accustomed to withstand this Taunami's of lactic acid.
In he beginning years ago I had to rest in between properly or the wt lifted / reps suffered but with time my arms think
"hey this is normal - This is how we work now- no problem "
I put one of my training partners on this and who trained biceps first or triceps first and dude was in mega pain and achieved massive pump. He had to ask me, I need to stop can't continue but he is getting well used to it. I could ever see me doing straight sets again. I have tried and it's not challenging. My arms crave for brutality and I end up going back to this routine.