Bad balance is mostly caused by bad posture. Try this. Feet together arms straight down by the side with the thumbs on the seam of a pair of trousers. Now rise and fall as we would when we dancing. Put the thumbs further back. It is probably still comfortable, but now the chest is pushed forward, no good for dancing, big front , small back. Try putting the thumbs forward, with you does this create bad balance. It does with me. To me this proves how critical balance is. If I want to get as high on the toes as those we see on video. We can't if we are even slightly off balance. I was stuned by one of the top dancers, a male , I could see the whole sole of his shoes right to the toes as his feet came together. As Micheal Barr, the comentator for the Amatuer European and World Championships. He repeatadly says how strong the ankles and feet need to be. But without balance it will not happen no matter how strong you may be in the feet and ankles.

Alignment of the body over the feet is one critical component of balance. But strength of the feet is another, no matter how good you are, sooner or later you will get a tiny bit off balance. Strong feet that can support your body weight at their extreme edges can help you move it back to the center, while weak feet can't. This isn't something you think about, it's something that just happens if your feet are strong enough and you think about aiming your weight for the right part of your foot.

i have two points i'd like to bring up.
First, on balance. Yes, absolutely essential in any sport, especially dancing. As we get older, our balance can be more problematic. Injuries to the ankle and foot especially can affect balance in the long-term but the good news is that it is possible to improve your balance by re-educating the brain's response to nerve path-way signals from the feet. Here's a simple exercise given to me by a physio a few years ago when i injured a foot. I do this exercise pretty well every day:
Stand on one leg. Keep leg straight, not soft as in dancing. Arms out to the side, other leg bent and foot free (not jammed behind the standing leg - that's cheating!). Stand for 20-30 seconds, then close your eyes and keep your balance - if you can. Keep trying. Swap legs. I have found this very beneficial. However, it only trains STATIC balance. Dancing is a dynamic activity and 'balance' also includes good control of transference between energy of movement (kinetic energy) and body position (potential energy), especially in waltz
The second point, related to this first one, is on the comments about body rise onto the toes. Take the 1-2-3 of the natural turn in waltz. There is a huge kinetic energy at the end of beat 1. We've lowered from the previous beat 3, introducing some energy, and added to it with the drive on beat 1. This energy is carried into beat 2, then, as the left foot plants on a soft left leg, and we continue to rise on 3, this kinetic energy is transferred into potential energy and we rise higher than we would if we just pushed up with our legs. Don't underestimate the effect of this energy transference. Do the sums! Good technique allows smooth control of the transition, and, of course, a good long drive on beat 1 increases the effect. Next time you see beginners dancing, watch how they bob up and down without much benefit from this effect.
The dynamics of dancing are complex (because there are two people) and fascinating. There's room for serious research.

In my opeion, generally,the biggest energy ( dynamic energy , driving body weight away )generates at the moment on the end of 3 ( waltz ) . such as in natural turn. the following 1,2,3 as well as the stone horizontally threw to the river ... I noted also that I need to compress my BT actively to drive my body weight swinging far toward its position on the end of 4 in natural spin turn; end of 1 in open natural turn or chasse role or chasse from PP( lady ) ,rising occurs throughout 1 . I hard to say which time duration is the biggest energy generated in these particular figures . . Please talk more about this.
I love your idea about the use of sum effect and soft receiving foot to absorb body weight first then expell body weight out and there always is a room for refining and fasinating it is.
ylchen

Yichen. Something to watch for is using more towards the inside edges of your shoes.Anybody who strides more than they are capable will tend to go to an outside edge. Rumba Walks is one where it shows up. Men can take a bigger step ladies smaller because of the heel height. Higher the heel the smaller the step. Simple test . Go into a splitz position and watch that foot go to an outside edge without trying. Surprising how many people use an outside edge on a Spot Turn still.