It isn't unusual for OEMs to implement features not found in stock Android exactly because they want to offer an experience that plain Android just can't. Eventually, Android does catch up, adding those features and causing OEM chanegs to be redundant. Sometimes, however, Android's official version doesn't exactly replace sometimes more useful alternatives. That was apparently the case when Sony removed STAMINA mode from its devices running Android Marshmallow in favor of Android's new Doze feature. After no small amount of complaints, the latest update brings it back for the Xperia Z5 family.