My sports gambling has always gone in waves, usually by sport. I absolutely killed betting NBA games in the bubble just betting favorites to cover. I used to do really well betting MLB games based on starting pitchers. I almost think if you have a more generic strategy in a sport you don't follow as closely, you do better than if you "think" you know a lot, but aren't a sophisticated gambler. I've never done well in football, NFL or college. I used to do well in college basketball, but I think the house has caught up to some of the inefficiencies with the mid majors from the pre legalized gambling era.
I suspect in general, betting unders, particularly first quarter/half unders is a slight edge, because betting unders is a stressful way to live, so I think those numbers generally trend a little high, particularly for partial games. I think you get teams whose low scoring (Iowa) becomes a narrative, so their full game O/U are probably accurate