This is in response to a very thoughtful and excellent post by Kevin Levitt on his blog at http://www.budo-warrior.com/?p=55
I have to respectfully disagree about the necessity of randori type activity in training. People in Japan have been arguing about this for at least 400 years, but the randori folks have never achieved a noticeable advantage over the kata only folks. The kata only folks demonstrated the effectiveness of their training methodology throughout the Tokugawa era from 1600 to 1868, holding their own in challenges, fights and duels. I believe the key is that the kata system must not focus on techniques, but on higher skills such as recognizing openings, preparing feints, and dealing with surprises.
I've done both randori focused training, and kata focused for a while now. What I discovered is that my effectiveness in randori increases most dramatically when I don't do randori, but instead make kata training the center of practice. This isn't technique training, but well developed situational training where my partner controls the speed and timing of the action. To do the kata effectively, I have to learn multiple lessons about reading my partner's body set, timing, and spacing as she changes timing, spacing and speed I have to deal with.
I am always amazed at how quickly I can apply these lessons to effect in randori situations.
Randori practice on the other hand is intense and fun, the main thing I take away from most randori training is knowledge of what I'm doing that already works, and what kata need more practice. I can practice kata for a long time without doing randori. When I go back to the randori, I inevitably find myself much more effective. On the other hand, when I spend too much time doing randori, I find that my randori skills don't improve, and often they deteriorate. The chaos of randori doesn't leave enough room to focus on skill development and the desire to win can actually defeat the learning and improvement process as you shift back to relying on raw strength and speed to overcome opponents when your technique is insufficient.
Randori is fun, and it validates who has learned their lessons well, but I really don't think it is a good teaching tool. It is a great way for people to test what they have learned and find out where they need to practice.