They kinda just need to sell their manga, don't they? If anime is "just popular" and rises manga sells, it's enough, like with Blend S or Yuyushiki.
Blends S manga stopped airing in ~2020 and there is absolutely no reason to make second season. I afraid if gochiusa will stop publishing, then anime won't get new seasons. I thought so. But Kin-iro Mosaic looks out of this logic. It's not so popular but have 2 seasons and 2 films... why