But you are correct in that most of us 'need' slower speeds in order to make good ball contact. This because, IMO, we (the hackers of the world ) have an immature understanding of the function of the lower body and an inability to incorporate and synch the lower and upper parts.
What I found from doing my A3-A6 drills enough times is that there is a feeling of leverage in the swing. A proper swing also makes the inside out swing come naturally and "slows" it down. I can't turn my lower body faster than it naturally wants to turn. So, it's not an active thing to slow down. The club just kind of whips around my lower body as my upper body "catches up" to my lower body. While this is happening my lead arm rests gently against my chest.
I suppose I could "go for it", but it's such a complicated sequence I wouldn't change what I'm doing just to get a few more yards? This is very natural and feels really good at impact. I feel like I'm putting my body behind the shot. I suppose I could also improve the coordination, and put "all" of my weight behind the shot, but again, that would take a tremendous amount of trainig effort for a few yards of gain?
I think your point is well taken, that we amateurs should just aspire to hit what we can hit naturally. My next step is to reduce my number of putts, and to solidify my drives. At 3 out of 14 bad drives this last round and 48 putts I think I know what to fix.
Back on topic, my friend really needs to see a good instructor and will save some trips to the chiropractor. I just need some backup to force him to do so.