A lot of guys are going to tell you that you should change the sprockets and chain as a set but in reality I usually do it every other chain swap. The amount of wear they get depends a lot on the quality of maintenance and the way the bike is ridden. You say the sprockets are in excellent condition, then why would you want to change them? If you are questioning your diagnosis of their condition post a close up photo and I sure there will be lots of comments.
520 sprockets and chain are not stock so these have already been changed at some point. Stock was 530.