Steady on! I said the top bowyers can do it. Not that everybody should be doing it.The "40 minutes to tiller a bow" is missleading at best and b0ll0cks at worst.
Sure you can tiller a bow in 40 minutes if it's already roughed out from a clean even stave or a laminate.(Also if you are doing it regularly) but it shouldn't be your aim.
The point was that the majority of the work is spent on getting the bow as close to final proportions as possible, getting both limbs even and the dimensions super close. Tillering for the experts is like a final check that all the hard work done on the bench was correct.
The rest of us have to use tillering to do half the work - that's where we find out what's working and what isn't. It's not a bad thing, it just reduces potential performance. If the bow is on the tiller for 30-40 mins, just being checked and worked to full draw rather than constantly pulled, released, pulled, released, removed, worked on, pulled, released... You end up with less set and more oomph. Not so much with yew, but certainly with white woods.