I would not clip the feathers of free-range birds as sometimes a little flying ability can increase odds a bird will survive an attack. Flying ability also helps with accessing more practical roosts and elevated nest boxes.
When I comes to actual clipping of wing feathers I have first hand experience and did it with one and two wings. First, you must clip the wings close enough which is very frequently where people go wrong. Too much feather remains allowing for some thrust production hence flight ability. Do not cut close enough to damage tissue. Secondly, chickens can clamber up things by climbing and running at same time up a vertical or nearly surface. Birds with one wing intact are more capable of than when both wings clipped. When I had birds that could not be contained by clipping one wing, they could contained following clipping of the second wing.