Thinking about it, ki-ken-tai-ichi is integral to everything we do in kendo and I have talked about it in other posts, but tenouchi is particularly relevant to making small waza work. Personally, I do not have a preference between big and small techniques. I believe that you should have both in your kendo armoury and use them to fit the opportunity. Kote is by definition a small technique as distance is closer than for men and you simply need to lift over your opponent’s chudan to strike. So the choice of big or small techniques is primarily for men.
Nuki men is a great example of big technique. You have to lift your hands up above your opponent’s kensen to avoid his attack. Tobikomi men too can benefit from a big furikaburi, lifting your hands above your mengane and taking your kissaki back 45% degrees or so behind your forehead. I find that this works against opponents with strong chudan kamae, particularly if you make the attack with a feeling of sutemi.
However whether we are talking about big or small techniques, none of them will work without correct tenouchi and wrist action. If your wrists are flexible, (see my post from July last year on holding the shinai), you should be able to strike men cleanly on top. If your wrists are stiff, either because your kamae is incorrect or because you are gripping the shinai too tightly, the shinai will land at the wrong angle and either strike the mengane or slide off the side of the men.
Chiba sensei showed us a great series of drills to overcome this problem. At first, he explained that for speed and flexibility, the cutting motion should be elliptical, with your hands coming down towards the top of your head as you start the downswing. He emphasized that in suburi, bringing the shinai back against your buttocks, as in the illustration above serves two purposes, it acts as a warm up, and it teaches beginners how to find centre. It is not the way to hit men. He demonstrated that the strike should be through to the chin and that the squeeze from the right hand should be just after the hit not on or before. Above all, he stressed that arms shoulders and hands should be free from tension.
At his recent UK seminar, he prepared the ground by telling how he practiced 4000 continuous suburi everyday, he then asked everyone to do a mere 200 using an opponents shinai, held at head height as a target. The psychology is simple, people were relieved at having to do only 200, but as this was more than the standard set 20 or 30 they relaxed from the start, saving energy for the last few. The drills moved on through a series of large and small techniques, both shikake and oji waza. By and large even people with particularly stiff kendo were able to be much more flexible and were successful with a far wider range of waza.
I think this is the key. If your shoulders, elbows and especially wrists are relaxed enough to do big techniques correctly, then it is equally simple to do small techniques. The choice is simply to find the most appropriate technique for the opportunity. In fact if you do enough kihon practice, the choice should make itself, but that is another subject.