I don't agree that training only twice a week results in poor performance and progress. I understand that more classes mean you don't forget techniques, you get more practise and it is a sign dedication. But on the other hand, others may find the same amount of training too strenuous or ill-suited to their life-style/reasons for training, and detrimental to their progress. And there are people like myself who are unable to attend classes more than often, (while TKD is a very important part of my life, I'm just not at a stage of my life/education where I can focus entirely on my training), but make up for it with enthusiasm and dedication. While I find TKD very addictive and would enjoy more classes, I don't necessarily think that my ability would improve because of them. I practise at home, get regular excercise and I'm always running through techniques in my head. In class, I'm focused on what I can achieve, and also what I can work on for the next lesson. I haven't found that my progress has suffered in any way at all. TKD is a way of life that doesn't just exist in the Dojang. Just because one does not train 5 times a week or more, it doesn't mean that person is any less dedicated to the art. I think it's more about attitude, and how you use your knowledge and time. A common 'mistake' I've noticed is shyness inhibiting ability. Many students, (particularly new ones), are too shy to kihap and use full power. It's a sign that the pupil is not comfortable in his/her ability and with fellow pupils, and while this should improve with time, if an instructor and fellow pupils don't make an effort to help to build up that person's confidence, it can often act as barrier to the student's full potential for quite some time. Also, I agree that a lack of control is a common mistake, particularly in sparring. Sparring isn't just about beating your oponent. When I first started sparring, I found it very intimidating, and with certain partners, I didn't learn anything except for how to run away from them! In contrast to this, what I learn from patient, more mature students, is invaluable and irreplacable.