Another volume with a totally unrelated side story just wedged in between 2 directly connected normal chapters.

It's even creeping up in anime too! Some character will show up for the intro of an episode or something and then you'll won't see them again for like 5 episodes.

the the main story and side stories seem to converge

Oh, I like it when stuff like that happens. I read one Sci-Fi book a while back that used this as a super cool misdirection. The story opens focused on one space battleship. There's a war and it's basically hunting another space battleship. You get to know the Captain and a bunch of the crew. Then the perspective switches to their enemy, the other space battleship. And you get to know their Captain and their crew... and they aren't evil or anything. Both parties are only fighting because there's a war going on. So you start to empathize with both sides. BUUUUT I started noticing that one ship started having more named crewmembers than the other one so I was able to figure out which ship was going to win before the end. Still, I was like, "why the hell are we switching perspectives so much" when I was first reading.

basically skips over everything that could be interesting and rather spends around 70% of the volume on the same joke

"They get ready and then this MASSIVE and AMAZING battle happens! But enough about that! After the battle ended, Curly gives Moe a wedgie. FUNNY RIGHT?!"