K* recommends somewhere between 5 & 12 degrees for optimum knees out.
In this one K* says "The knee can be completely safe and effective with somewhere between 3-7 degrees of foot turn out."
Diane Fu has strong "external rotators". What are they? I need some of those.
Also, with feet straighter you have more power in the external rotators to keep the knees out. I would never have thought that would be the case, so interesting.
Notes for self: "Yes, better mobility and addressing the other factors Kelly notes will allow you to keep your feet straighter and not lose torque. Other episodes to look at are 230/365: Squatting With Turned Out Feet? Hey Duck Squatter, IR Yourself Episode 274/365: The Standing Athlete,343/365 Stop Walking Like the Duck You Aren’t"
link from 70's big on this
and Catalyst athletics article in reply to K*