I will state this one last time. A chicken on the planet Earth cannot jump 8 feet. Based on what you have stated to date, you have not seen a chicken jump that high. Rather you saw a chicken jump and continue motion my continued effective flapping of wings. To get more than 24" above the ground an adult chicken needs assistance from the wings. The wings provide thrust not unlike a helicopter taking off. Most of that thrust is provided by the primaries, especially the outer half of their length as that is part that bites into air as bird produces power stroke while flapping. Flexible tips of those feathers are really important for that process to work. The inner part of primaries and secondaries produce much less thrust, but their contribution is not zero, hence the reason more aggressive clipping is being employed. it is possible with the more aggressive clipping that some of the birds may not be able to access the coop even if I lower is back down to the 36" setting.