I always find it amusing when a student says they know a pattern or technique. This is very common, especially when requesting to grade or young members get bored with a pattern because they "know it". It is understandable as to why this is so common, mistaking knowing the sequence of steps for knowing the pattern. The truth is, to know something is to have reached perfection. It is impossible to reach perfection! It is therefore impossible to ever fully know a technique.
What should be strived for is to get as close to perfect as possible. That is our aim, with this mountain that has no peak.
This can also be said especially when one reaches black belt first Degree. Many see this as the end goal, while it is actually only the beginning of ones training after passing through the basics.
Also some believe that once they believe they can beat another person, they now know Tkd and need not continue anymore. Well, that is a whole other story, with a person not understanding that the training is about self improvement as discussed before.
Lets try to persue perfection in every technique and aspect of training and not rush through to only know the sequence without a deeper understanding of the mechanics of each technique.