Here are some drill sequences using this movement pattern (pushing and pulling two feet together using muscle action):
Stand on flat snow. Push both feet forward and pull both feet aft. Don't fall over.
Slide straight down a shallow pitch. Push both feet forward and pull both feet aft. Don't fall over.
Make round turns on that shallow pitch, pushing both feet forward and pulling them back while turning. Getting good!
Take it up the hill. Make medium round turns on gentle terrain, pushing both feet forward and pulling them back between turns, then through entire turns. Very good now!
This is still a drill; it encourages versatility, and prepares you for recoveries. But would anyone want to ski this way? No, but it's worth doing to increase balance awareness.
Another application of the two footed push-pull: stand across the hill; sideslip down. Push both feet forward and sideslip backwards down. Pull both feet back and slideslip forwards down. Do this backie-forthy and you've got one version of falling leaf. As a drill this illuminates the impact of being forward or back on flattened sliding skis. This is not just a drill; it's actually useful in some tight situations.... (Falling leaf can be accomplished by opening and closing ankles as well, but that does not involve pushing and pulling the feet which is my topic.)
Let's up the ante: do the two-footed push-pull thing while skiing along on a groomer, but add vertical "oomph" at the end of the forward push. Propel the skis up into the air! Pull them back behind you while they're in the air, and put them down behind your hips, tips first. You've got dolphin turns! A très-cool trick involving serious athleticism, but still in essence a drill.
Let's up the ante another way: on a shallow pitch do the two footed push-pull, but add rotary. Pull them back behind your hips, then push them way out to the side and around to in front of you. Then pull them back and push them forward and around on the other side. Pull back, push out and around to the front, pull back and push out and around on the other side. Keep them flat enough to slide them around muscularly in a very-very-short-radius turn under an upright torso. You're moving your feet in a sideways figure eight beneath your hips. Bumpers do this drill on groomers to prepare for skiing the zipper line. (Can't find video right now but I know there are plenty out there.)
All these are variations on the two-footed push-pull drill; usually they are not ways to ski. They are not efficient; they are athletic and elevate the heart rate. They do not focus on flow.
Once you are skiing with one leg long and the other short, the two-footed push-pull action doesn't work so well.
Edited by LiquidFeet - 11/1/13 at 8:43am