In an age where purple belt seems to be just another belt in BJJ I have GREAT respect for a person holding this rank. Not many people who start BJJ will ever receive one. Purple belt is like a black belt in another discipline. They have typically studied with me for around 5 years. They are truly someone special. They are now in the club and have shown me they are a serious student.
It is for this reason that I think purple belts need one-on-one attention from the instructor. This is the time where purple belts are dying for the "cool stuff." When I teach class I will teach a move and then individually show the purple belts add-ons to that move that no one else gets in class so they feel special. This is where they typically see me most, is at this level. Because they are special. They deserve it.
This is also the belt where quitting is so tragic. This was the toughest belt to get. It's all downhill from here (theoretically) toward black belt. It would be terrible for an instructor to let that student quit or for the student to let himself quit.