When skeletons drop bows, they are supposed to be fully usable, and not have any uses used on them.
However, while killing skeletons, I realized that I had gotten a bow that had very few uses left on it, and you could see that the bar depicting uses was nearly depleted.
Steps to Reproduce:
1. Open a world on either creative or survival
2. Kill many skeletons and hope to get a bow
3. Once you have gotten a bow, see the uses it has left.