I have not tired out volume training above the 50 reps amount. But as I've gotten older, the lighter weight, higher volume training has been very helpful for me in avoiding injuries. In my 30s a nagging injury lasted 3-4 days, in my early 50s, those same injuries last 3-4 weeks. If you see the journey as a marathon rather than a sprint, you make more slow, steady progress.
And I'm also convinced that the volume helps provide more density and hardness. The classic look of the 70s and 80s may have been a function of the overtraining that many of those guys did. Sure, it affected their size, but did some impressive things for their density and hardness.
On the very high volume sets, what are you even doing for the first 50 reps? If you're moving a weight that you can rep over 100 times, what stimulation are you achieving for the first 50 reps? With light weight, I feel like I get more blood volume to the target muscle group, but only in the last 10-20 reps.