I have no coaching background, but sharing my personal thoughts –
100km / week is a lot already, probably I’d add Muscular Endurance and/or interval sessions (which don’t consume as much time) rather than long runs ? I ran Dragon’s Back and Ultra Trail Monte Rosa with that volume and finished in good conditions.
140km / week is pro territory, they have no work obligations etc. and can thus sustain this load. I would think 140km/week is too much stress on a normal person to be productive. But everybody is different of course.
With that said, many pro athletes train twice a day so maybe that is good to replenish and do a second run. With that volume, I’m not sure you need to do much body hacking like trying to run fasted etc.