My green belt surprised me last training session.
He's not been coming to training very much in the last few months, but has just started coming regularly again. But to my joy, he has been practicing outside of class and ... it shows. When I sparred him, he was much faster and smoother, had better coverage, and had excellent combinations.
He must have had the time to mentally assimilate a few skills he acquired while we were working on him a couple of months ago. He was due for a belt grading then, but did not make it ... so I'm really happy with the natural progression he has made by himself.