One of the added values of training and practicing is to increase your confidence in what you do and increase the confidence in yourself.
When it comes to physical sports as Judo, repetition of drills and techniques is essential to maintain good proficiency. The muscle memory needs to be as such, that you don’t have to think about what technique needs to be used, in what situations in the fight.
The problem is that confidence in the way that you perform the various techniques does not assure your confidence in thy self. For this, there is a need in a different type of practice, a psychological one.
The best psychological practice that I can think about is competition. Or, in other words, testing your ability as many times as possible, in “real” situations. By “real” I mean, situations that you cannot do “Ctrl-Z” or “Undo”. Situations in which any decision you make, has higher implications. Higher price to a mistake. In Judo, when in competition, the mind behaves differently than when in practice. There is a different amount of pressure that you need to cope with, and the mind needs to handle not only the physical constraints but the mental as well.
Sometimes, there is no direct correlation between the two types of confidence.
I’ve known guys (and gals) who sucked in practice, were thrown from one side to another the whole training session, but when they competed, it was like there is a different person on the mat. Full of self-confidence, these people blew out the competition, just by applying a great deal of self-confidence.
Now, I am not saying that being self-confident is enough to win the competition, but it raises, to my opinion, the chances of you winning, by more than 30%. the rest is skill and physical endurance.