The think about really high rep approaches question is how helpful can it be? I mean if I make 99/100 putts from the exact same spot, how helpful are those last 50 or so makes in a row? What if I miss the first one but make the next 99 in a row? In a real golf situation that would just be a miss, plain and simple.
I suspect you're assuming that you always practice from the one spot. Nope. As I said eariler, I throw several stacks before I move. I throw from many spots during a practice session. Over the course of many practice sessions, I'll throw from a great many different spots, at different distances, with the wind blowing from different angles and at different wind speeds.
With consistent practice, over a few months, you'll have thrown thousands of putts. You will have made thousands of putts from short and long, upwind and downwind, uphill and downhill. You'll have developed a routine that you don't have to think about. You'll have refined your technique to where you don't have to think about it. You'll have trained your brain to focus on the target efficiently and won't have to struggle to concentrate. The more high quality putts you throw, the better you'll be at making high quality putts. It's so much easier to feel confidence about a putt when you've already made hundreds from that distance with a wind from that angle....