A third season of a highschool romance triangle anime only means 3 things: many episodes of bashfulness, non-committal, and pointless filler stories.
Oregairu gets plaudits because characters speak in a stand-out weird manner where every person has a witty/intelligent response to every line that is ever said to them. Its too forced. Nobody communicates like that, ever.
The triangle (and it IS only a triangle), just continues. You wait for progress, and you wait, episodes go by.... Finally a conclusion. What even happened in the first 10 episodes? Something about a prom that the viewer doesn't care about in the least.
But hey, it has cute girls who are still interested in a socially awkward MC that for some reason people think they relate to so it gets 10/10s and 9/10s.