Saitama being absent for most of the arc until showing up last minute and taking care of things? That happens in every major arc, but this is the first time it felt dragged out. OPM Manga might as well be a standard shonen with great art right now. It's been a while since I read it, but I never felt like the MA and Garo stuff in the webcomic was dragged out at all. It also helped that the Garo arc focused on, you know, Garo. An actual interesting character and not these lame ass tournament characters.
There was a point where I was anticipating reading every new update of the manga, but now I just kinda wait until Viz Jump dumps a bunch of chapters. Every time I read it I just want them to go back to the Garo stuff already. It's weird since the beginning of this arc was following the webcomic pretty faithfully until it split off to do it's own thing. And that wasn't a bad thing at all at first. The stuff with Metal Bat was a great addition that I thought added a lot to the arc. Everything after has been a chore though.
I figured the Garou arc would get a similar reaction as it takes the shonen stuff far more seriously in general and Saitama is absent for large parts of the largest arc by and far. A lot of awesome stuff happens but the S Class heroes and Monster Associations show for a good portion of it.