The Dragon TV show isn’t half bad and the Trollhunters franchise is great, though everything else is garbage. That’s the problem for animated sequels that Dreamworks hasn’t learned yet, the last time they had a sequel increase was with Madagascar 3. Kung Fu Panda 2/3, Penguins of Madagascar and Dragon 2 suffered from their TV series not because of quality but rather easy accessibility. Considering how expensive the movies are for families, why pay $60 for the sequel when they can watch the series at home. Croods 2, Trolls 2 and Boss Baby 2 are screwed because of this as well. Also I think the vast amount of Lego Batman and Ninjago DTV movies also hurt the franchise as well.
Illumination and Pixar (and to a lesser extent WDAS, despite Ralph 2 being uneventful it increased even if barely) got it right, they waited either 3-4 years for number 2, and aggressive marketing/shorts in between, or if story problems arise wait 10-11 years and let nostalgia take its course.