The ostrich, penguin and bat are notable exceptions - there we find feathered wings that don't fly, and flying wings that don't have feathers. And of course there are insects too - flapping wings with no feathers, just like a bat. So perhaps it's the flapping wing that's really the best practice, not so much the feathers.
But in fact the early aviation experiments involved both flapping wings AND feathes (think Icarus). It's not all that different than cargo cults.
However, it turns out that in order for people to fly, we're actually better off with fixed wings or rotary wings. Just something to think about when it comes to imitating "best practices."