Saving animation with keyframe inserting location and rotation While saving an animation clip with keyframe of armature pose, should I select all armatures and insert location and rotation or can I just insert changed armature's location and rotation?

I selected all bones and inserted new pose. Working great. But doesn't seem to be the optimized solution. Character animations are being used for games in Unity.
You can insert the new animation to the keyframe of the armature who is changed. You can actually keyframe a new rotation of just one bone of an armature, so if you modified a bone rotation in pose mode you can then press I to insert keyframe and then choose rotation, and this will insert a new keyframe for the rotation of this bone.

I attached a .blend file where two armatures are there and adjusted the bone rotation of specific bones.