Would I teach them? No. Can they be done? Certainly.

The men who are leading you might not be executing them very well. But that doesn't mean it's impossible to do well. See my other post for a technical explanation.

As to why I wouldn't teach consecutive passing half-turns, it has nothing to do with whether or not they're possible. They're simply out of character with Waltz. To continually turn in one direction and travel down a straight line is more of a Viennese than a Slow Waltz thing. And there are better ways to get the job done. Anything wrong with a simple cross turn?

Regards,
Jonathan