My rule of thumb for any long show, specifically anime, is that if they have more than 30 episodes per season and have more than 2 seasons at the time of me watching it, I'm out.
I call it the "Ekta Kapoor Effect".
She's a well-known producer of Indian serials. Yes, those ones.
She's had this effect on the Indian TV market. Even regional shows that she doesn't make have this effect.
Basically, they pick an interesting social topic or issue, make their point in the first few months, and then proceed to just do a repeat of the typical "Mother-in-law and daughter-in-law fight", or "Artificial drama for the sake of drama" arcs that don't really make any sense, only because they want to keep people watching for as long as possible.