The devil is in the details, and so is good technique. If you practice too fast, you’re bound to miss things. But also, a lack of focus or simply not looking closely enough will cause you to make the same mistakes over and over again.
Most beginners simply lack body awareness. But even intermediate and advanced dancers are often surprisingly little aware of what they are doing. Learn to watch and analyze your movements, directions in space, levels of tension, posture and alignment, timing, connection, and so on.
Building up body awareness needs time, and it can always be improved. It’s absolutely crucial to heighten your sensitivity about what’s going on if you want to make major changes in the way you dance.