The latter is to make you understand that likewise in turning, one could be successful using one system where another would probably fall or loose his/her balance if they didn't adapt the way to turn according to their body type and the opponent they face.

It would be nice if everyone was able to perform as well as Sensei Ohta/Brennan/Roberts (to mention but a few) the truth is that we cannot, and I believe should not, try to emulate their ways as they are different people. What one should try to do is to understand that principle, and adapt it to his/her body type.

In life we adapt to different situations all the time, a good example is driving. We are all taught the same rules, how to change gear, look at the rear mirror, use the indicators; and keep both hands on the steering wheel, but a good driving instructor knows better than assume that we will keep on driving that way even after we have passed the test.

Turning is similar in that respect, as we are all taught in a very traditional way example "move the back leg anticlockwise 90 degrees landing in Zenkutsu-Dachi and blocking Gedan-Barai with the left arm".

Most instructors teach without thinking that the practitioners are individuals, therefore the above is the only thing that they say to them and assume that the group they are teaching will be able to turn properly as one. What you get is a bunch of people stepping/trampling and blaming each other's incompetence.
Turning is not as easy as that.

In Judo, one is taught how to throw the opponent by moving in or across but above all, one is taught to find his/her own balance. In Karate as well as many other Martial Arts, we are taught how to kick/punch or strike but very few teach us about balance.

Are we supposed to learn that without been taught?
You must first:

• Understand what you are supposed to achieve in that Kata
• Understand the applicability of the turn
• Understand which part of the foot you pivot with
• Understand where your fulcrum is
• Understand what the rest of the body does while you turn

I suggest the following exercises in order to achieve a better understanding on how to turn.

1. Take a stick (a broom stick will do) and hold it behind your back at hip level, in whichever stance you are supposed to be in during that particular Kata position. Avoid bobbing up and down while turning, keep contact with the floor at all times. Rotate clockwise or anticlockwise according to that particular Kata, but remember that this means that is your body that turns clockwise or anticlockwise, and not your legs/feet,
2. Write down the different turns you need to practice (i.e. write down in details which leg moves, what the arms are doing, are the knees meant to be together etc. etc.) By writing-down the above, you will be more aware of the problems surrounding such a task.
3. With most turns you must Pivot on the Heel of the Supporting Leg.

Sometimes in order to turn smoothly, you will require adjusting the "NORMAL" way to turn, and still be OK in the eyes of the Referee/Judge or Examiner assessing your performance. Above all, try to understand the principle behind that particular turn, because as you already probably know, every turn is different. The applicability of each turn will became more obvious when you are shown a way by a Senior Sensei and then you are asked to try it out with a partner. I am more than sure that you will agree with me, that some applications will be easy with one opponent and completely useless with another. We have all "been there and done that" I remember many instances of failing to "perform well while trying to turn and strike accurately" as Sensei Kawawada was watching us during the last Crystal Palace Course. It is all to do with "feeling" the move really "feeling it". My partner had no problem at all; he was "feeling at home". Yet, when we changed partners, I was the one "feeling OK".
The latter happens all the time, and we are quick to blame someone else, but after all, it is to do with been confident in that particular technique or Kata.

In my experience, turning should be as smooth as possible as it is the most vulnerable movement (transition) we have in a Kata.
The first turn in Heian-Shodan (after the first Kiai) for example, need to be performed keeping in mind the direction of the technique which follows the last Age-Uke, which means that the back leg should travel almost directly towards the next opponent, as you are supposed to stop them in their tracks (De-Ai), therefore do not bring your knees together but instead, use the supporting leg (right one in this example) to withdraw the back foot, and rotate the hips/upper-body anticlockwise preparing the arms for the Gedan-Barai that follows, and thrust the left leg toward a left-front stance, making sure that we are pushing the weight towards the now front knee (left one) as we strongly block downward with the left forearm.
The latter rotation should make use of the right heel as hinge and moving the toes around it in an anticlockwise manner.

Another example is the move (just after the first Kiai, Kyodo number 13) in Heian-Yondan, when we need to pivot using the right heel as hinge while rotating the toes around in an anticlockwise manner, the arms will cross in front of the chest (fists just above the shoulder level) then they rotate outward as they are lowered to shoulder level, and shoulders width and the left fist slightly in front as the elbows are kept at one-fist width from the sides of the body, while the left foot is travelling to end in a Migi-Kokutsu-Dachi (right back stance).

The most dreaded turn within the Heian Kata must be when we turn to face Shomen just after the last Morote-Uke in Heian-Godan. The latter needs some work in understanding what is happening with the hips. As the upper-body rotates anticlockwise, make sure you are not loosing the hips by allowing the right heel to slide backward, while the left foot moves diagonally just a little to allow for the right hip to move forward (Shomen) into Hidari-Zenkutsu-Dachi (left front-stance) in order to strike Shuto with the right knife-hand, immediately after that, the right hand clasps into a fist, and moves upwards just in front of the face in order to end up as Migi-Uchi-Uke (right inside block) behind the head, the elbow should be at the same level as the shoulder (Kyodo number 21) while the right hip pulls the body weight slightly back in order to achieve a Migi-Kokutsu-Dachi (right back-stance) the left hip should not move too much and the left knee should remain facing Shomen at all times. The next rotation which gives nightmares to most is the last move of this great Kata (Kyodo number 23) this will start as we are standing in Heisoku-Dachi (feet together toes together) prior to the rotation. Keeping the left heel firmly grounded, slide the right foot towards Shomen (keeping your feet almost aligned) and into a Migi-Zenkutsu-Dachi (right front-stance) in order to strike Shuto with the left knife-hand, immediately after that, the left hand clasps into a fist, and moves upwards just in front of the face in order to end up as Hidari-Uchi-Uke (left inside block) behind the head, the elbow should be at the same level as the shoulder (Kyodo number 23) while the left hip pulls the body weight slightly back in order to achieve a Hidari-Kokutsu-Dachi (left back-stance) the right hip should not move too much and the right knee should remain facing Shomen at all times.

A further example of awkward turning is brought to us compliments of Heian-Sandan Kyodo number 9. Start to Pivot on the ball of the right foot half way (until your toes are pointing toward Shomen, and rotating the body anticlockwise) then keep the right heel firmly grounded and move the toes anticlockwise to end the rotation in Kiba-Dachi (horse-riding-stance). To achieve this, the movement should be smooth, keeping the whole foot constantly in contact with the floor surface.

In Jion, after the third punch to the left side at about 45 degrees (Kyodo number 6) we move towards the right at about 45 degrees (Kyodo number 7) and in doing so, we need to be careful not to loose the hips by letting the left heel slide away, instead, we need to stand our ground by pivoting on it, allowing the toes to travel clockwise, while the right foot slides into position (Migi-Zenkutsu-Dachi = right front stance).

The above are only examples of the many more turns used in our great Shotokan Kata.

One more point to try to keep in mind is that when the Examiner/Referee/Instructor say Naore (return to Yoi/Ready position), one should keep the back heel in place and rotate the toes in order to achieve this (example: after the last Kiai in Heian-Nidan (Kyodo number 26) Hidari-Age-Uke (left upward-block) Hidari-Zenkutsu-Dachi (left front-stance) transfer the body-weight onto the right leg, keeping the right heel firmly grounded and turning the right foot toes anticlockwise, while the left foot is brought back into Hachiji-Dachi (feet apart natural stance).

All of the above is my experience and does not reflect the views of any other Instructor within the JKA England. I do not say "this is the JKA way" I just say that I find the above helpful in my performance of Kata.