Episode intros and outros are just meant to be filler. A universal way to save on production costs and lengthen the time between ads. In the case of anime intros and outros, record companies also use them as a form of advertis.e.m.e.nt.
Anime intros are standardly 90 seconds long and thus very easy to skip. Thus, even if it''s the intro of an anime that I''ve watched for over a few hundred episodes, I almost certainly won''t be able to recognize it by the music alone.