naruto: shippuden is almost as long as the original series, i think.
its been over a decade since i watched those shows, and dont think i could really tell you wether they are worth or not. i also didnt check out the new bleach anime, since im mostly out of anime at this point, with the exception of one piece and maybe a season of something else every 1-2 years.
following this i would say when you stop wanting to be grown-up. and that certainly tracks for me