Season 1 and 2 are formulated so that they are like two short seasons of anime, each containing multiple shorter arcs! Around 20-30 chapters each for around 12 equivalent episodes. That's how I like to think about the stories anyway.
Season 3 is going to be a long one, akin to a 26 episode season with around 60-70 chapters! It's going to be a fun (long) one!
EDIT: The later part of season 3 is moved to season 4 instead, where it allows for a more cohesive story in season 4. That means season 3 will also be a complete story of around 30-40 chapters in length!
For season 4 and beyond, it is likely to take the format of the later of the 3 seasons, as more complex and hype story arcs that require longer built up and progression will be written.
Have fun and keep filming!