Dai is weekly, they just managed to convince someone to let them get two cours ahead of broadcast before airing the first episode. As a result the amount of good shots in the series is staggering. Shida Naotoshi usually only has time to do a short scene but the extra time (as well as mostly working only on one series) has allowed him to do a ton of animation for Dai, including animating the entire first Opening by himself! I'm not sure what the situation with World Trigger: Second Season was but the schedule was going enough for Oota Kazuhiro to solo Episode #2 and produce several minutes of exciting animation for it, too!
Iwane's episodes have had long-time animation supervisor Shimura Izumi as a second animation supervisor since SM began. My guess is that someone wants his episodes more on-model for whatever reason, which is a shame. Nevertheless, Iwane's speed and variety of skill are unheard of. No other animator on the planet can be trusted with solo key animating an episode like he does while also producing exciting action, character, comedy, effects, liquid, fire, smoke and mecha animation in an episode. Even more amazingly is how he's doing this in his fifties! My hope is that Iwane will be given more time for future episodes, though, but that also means hiring more animators and re-arranging the way the story unfolds. Back during DP they re-arranged the schedule so that Iwane could skip two cours so that he could solo #187-188 and #191 while also working on the other Shin-ou League episodes as an action animator. I'd love to see that done again. Similar was also done with the schedule for Mega Evolution IV and the seventh XY gym episode as well as the eighth gym!
