What breed/s do you have? My older flock is EE, BO and BL. My youngsters are BA. We trimmed one wing on the littles. We have found that after their molt they usually do not try to fly any more. I think they either forget that they could fly, or their bodies get too heavy as they mature. Perhaps a combination.I wish my chickens were like yours! All of mine fly over their 8' fence, and then they can't get back in, so I have to leave the gate open for them all day. I'm planning to get bird netting over their run soon, so that should help.