Hi volume works, if you have naturally high aerobic capacity and improved it to marathon levels with years of hard work.
Some people can run a marathon without much training, it is similar to that, genetics play a role.
A medical doctor friend of mine said it is perfectly normal to defecate 3 times a day
Or once in 3 days
This means there is 9 times difference among two healthy individuals.
Same goes for natural energy levels and tolerance to training.
Arnold was blessed with high energy, read the article.
He worked like a maniac and outside the gym he was so active, chasing pussy, pursuing business deals, being social animal he is.
Tolerance to frequent training is a gift, if you have it, you "should" train frequently.
If you have normal energy levels, you just can't emulate high volume no matter how driven you are.