The good news is, putting a knob in the middle of the green is the best way to both require exceedingly good approach shot accuracy, and is also the best way to foil good putters, who can judge a constant break, but have trouble judging a break that occurs half way to the hole, because they won't know exact ball speed.
The bad news is, putting a knob in the middle of the green is the best way to both require exceedingly good approach shot accuracy, and is also the best way to foil good putters, who can judge a constant break, but have trouble judging a break that occurs half way to the hole, because they won't know exact ball speed.
More good news is that a knob serves similarly to a tier or valley in dividing a green, and is more subtle. I believe (but could be wrong) that they fell out of favor at least partially due to the sand based USGA greens because they tend to overly dry out and require hand watering.