Here is a beautiful example of a winged foot - not too much prolongation.
I found this article in Dance Teacher Magazine, Theory and Practice: Winging (and Sickling) It, to be very helpful for not only spotting sickled feet and how to fix them, but also being wary of winged feet. Both can be signs of weak ankles. This article outlines exercises dancers can do to strengthen the ankles to prevent injuries. Check it out!
- Dancers with weak or untrained ankles are more likely to sickle their feet
- Winging can become dangerous if that foot is supporting weight, so use caution when teaching students to wing their feet.
- "Those teachers who approve of winging should explain how a winged foot fits into the classical line as a whole, to prevent winging from becoming an empty affectation."