Mario Tobias

Adding from above replies. A technique can sometimes work when it's done fast but the issue is it won't work all the time when faced with some partners. You can only learn the deeper aspects of a technique if done slow and it still works. Speed only gives you false sense of security.

The best example I can think of is Saito senseis teaching methods. It is not dependent on speed at all rather maai, timing, relative position, precise footwork, body/hara movement. He can stop during a technique and make it still work because everything else is precise.

So rather than working on speed, work on correctness/precision of the above. If you can do techniques fast, but done "incorrectly" then it may form part of your bad habits. Bad habits are often difficult to eliminate. Of course how to know what is correct is another topic for discussion.