In some cases, yes
but the Stranger Things posters have so far been pretty accurate in terms of summarizing character focus in each season. I mean, didn't the second season poster make Steve much bigger than Jancy too? And that pretty much reflected their limited screen time in that season compared to his.
Maybe you're right and I'm overthinking things. Then again, it's hard not to, when the show has been off air for so long.
I still can't help but think that Billy will get more screen time than the Byers with his stupid seduction storyline.