I like the show and I understand your point but they could have struck a balance. They could have included more infected without it becoming "mundane and boring".
I know that they are leaning into the drama/emotional side for this show (I've talked about this before in this thread) and I'm fine with that but they still could have included more infected.
I know that some people will say "Well, that's unrealistic" but the entire premise of the show is unrealistic and it's literally based off of a video game. Also, what Joel did in episode 8 was highly unrealistic (and I love episode 8). Joel basically turned into the Hulk after 2 doses of penicillin
Joel would still be out of commission for a while even after receiving the penicillin (also, Ellie didn't administer the penicillin properly). Joel is also lucky that he isn't allergic to penicillin either