Thanks Don. Strong ankle and keeping the straight line through the shoulder blade on same side leg and foot is the effective way to stand on out/edege of BT. I swung and turned on 4, 5 for natural spin turn torward the LOD, ( left BT back and slightly left on 5, turn , down on first half beat, then rising and out . I thought, the sumps effect ( phil said here ) from &( 3) to & ( 4) may be the way to expell me out easier and farther to fit my coach body swinging and long stride. He released more his abdility on last lesson, I felt I had to re-adjust myself to keep light connection and enough room. I had a little bit panic and tired when we repeated the routine. It is hard to do to bend big stride and smooth motion together and let it look easy. My God.
The exercise you mentioned is good for better balance and strong muscles , ligaments and ankles , even muscular memory. (I stood on suporting BT, upper limbs hung side ,closed eyes, lifted other knee for 2 bars, then swapped over .

)
Outside edge of shoe can be used in particular line fingure , such as hinge . Our knees should be kept within feet . to avoid from ungly foot work and leg shaping or out of balance . The major suporting part is inner half ( 2-3 toes involved ) on the tips of BT .( little finger dose not touching floor at that moment , especial swinging to side way ) Bigger unit pressure has bigger reactive force to hlep lady extend her body and head line ,( such as at the moment on 3 , turning lock to right, ) in common situation , less unit pressure less soft tissue injury, I tranfer my Body weight from i/.e of BT to bt ( all toes without body weith out the gravity line of receiving leg ) on 5 ( natural turn.)
ylchen