Crossposting from the other thread since we're talking about anime lenght here as well:
Katana is a fun fight with a (fairly) upbeat ending with
while wrapping up a good portion of story beats. It also has everyone easing up a bit for the first time in a while, while ending with Denji and Power starting their training, setting up new characters. And you can probably end the season on Reze coming to down, with a little rat running by her feet for some foreshadowing :p
That way it sets up a lot and allows for a lot of fan theories to start forming, you're left with "what the fuck is Makima's deal?!" a wrap up of Denji and Aki finally bonding a little. A lot of emotional highs and lows are hit for the first point, Aki grieving over his teacher's death in the hospital and if I remember, going to make a new deal with the future sight devil. You can end this season showing all of these characters heading down their new paths with a lot of clear cut goals.
I feel from a pacing perspective, ending season one here gives people time to breathe and animators a chance to relax and also amp up the budget again for the bomb devil arc.
