The lack of screentime for certain characters is because of....

The way the season is structured

Looking back, every season has around 3 major groups throughout the story, as there was always multiple storylines going on that all connected in the end

Season 4: The Russia group, the California group, the Hawkins group

Season 3: The Russia group (again), The Mall group, the hawkins group

Season 2: Jancy, The Lab group, Steve's group

This helps split up the screentime, which each group getting approximately the same amount of time. It felt that every character was seen throughout the show. Each group has there own stories and own arcs going on, so it feels as if

in Season 5, we have

- The First Upside down group (Hopper, Eleven,Kali)

- The second upside down group (Dustin, Jonathan, Steve, Nancy)

- The memories group (Holly, Max, kids)

- and then everyone else

The problem is with how intertwined and overlapping these groups are. The first upside down group comes back in the beginning of volume 2, now giving ~10 characters in a single space. It becomes hard to focus on all of them when they're all connected in one story

A lot of this is due to the storyline about Henry's mind. Although interesting, theres only really 2 major characters, and they get a lot of the screentime. If we could've gotten Eleven and maybe Will in this group, it could've opened up more screentime for Joyce, who had close to nothing in Season 2