I guess it depends on the manufacturer, but years ago Yamaha only had about 3 different oil filters across their whole model range, wheel bearings were common too. Suzuki though had virtually no consistency. You would think that rationalizing parts would save a company lots of money in manufacturing and spares holdings. Now selling them as spare parts is very different, if you were unscrupulous you could sell identical parts but labelled as bike specific with model specific part numbers. Mmm, how many are guilty of that? I know a couple of brands!