I think it depends.
If your chickens are confined to a run where the ground has become quite soft, there will be nothing to wear down their nails and they can become long and deformed.
If your chickens can free range, at least part of the day, then the scratching of different surfaces may keep them to where they don't need to be trimmed.
It's kind of like dog nails. If your dog lies around the house or the yard all day, they will need their nails trimmed, but if you walk them on the road often, their nails will stay short... or at least short longer.