Dang, that is hard! Where there is a will there is a way I guess. Both wings clipped or only one? It is my understanding that only one is better since the difference in lift on one side screws them up.
One reason my birds might not fly fences is that they have more room than they can possibly use so they really aren't kept out of anywhere "interesting". They know they can walk around the fence so why bother going over I guess. Still it seems odd that if they run when they want to go somewhere fast.
At first I clipped just one as I had also heard that it affected balance and would discourage flying. It didn't - then I tried both on the ones flying. The clipping I'd done, more or less, made no difference at all.
Mine have half an acre which isn't a massive space but it isn't as though the 17 of them are enclosed in a tiny space or anything.
It does amuse me a bit. Mostly my cockerels will be the one to hop the fence into the preschool yard only to immediately freak out when the 30 or so children start playing "CHASE THE CHICKEN!"
The teachers came to me and said, "I don't want them to hurt him! I try to stop them but they're so excited!
I respond with, "Oh let them. That'll teach the little jerk to fly over the fence if every time he flies over he gets mobbed by kids. Maybe it will make him think twice about going over.
We had an incident recently where I heard one of my cockerels crowing from somewhere decidedly not my yard.
I went hunting around and peeked over the fence. There he was. As soon as he saw me, he screamed. He knew he was in trouble. I pointed and yelled ,"HA! I KNEW you were over there! Bad chicken! I'm coming to get you!"
No sooner had I left my yard to walk over (where I had been heading anyway to pick my son up from school) than he hopped back into our yard. He knows when mum is serious!
My neighbours think this is hi-larious.