seeing how well KnY fanbook and Crocodile oneshots collection makes me think
should Gotoge takes a long break after KnY ends?
the momentum of the franchise is so big they can put out anything and put KnY name on it and it will still sell like hot cake
so why risk stopping the momentum? why risk having your fandom jumping to the next thing? why risk taking a break and then putting out another RxL/Hungry Marie/possibly Kamio and S8?
and in regards to taking time to plan and research for new series, they can do this side by side while working on KnY, we have a precedent of this, YOKO ended Dancing midgets in #11 then lunched Shoodan in #28
these are just my thoughts, if I was Gotoge, I would definitely not take a long break
Both Kimetsu and Neverland are in extremely fortunate, and quite rare situations now since they’ll be ending on a popularity boom and with anime content likely still to come years from now. AC and Bakuman both ended at a high for popularity, but their anime finished within a year or so of the manga. Kuroko is probably the most similar since it still had Last Game 2.5 years after the manga finished, but it’s not like there was something yearly to look forward to for fans.
Kimetsu and TPN’s anime are popular enough, animated late enough in the series’ lifespan, slow enough paced, and the studios’ outputs are small enough that we’ll likely still be getting anime from both years from now, particularly Kimetsu. At best a season 2 will come next Fall (unlikely), you’re probably looking at more than a year after for season 3, and there’s probably going to be enough content for a season 4/something else too. Even if it ends within the next 6 months at the earliest, we’ll probably still be seeing animated Kimetsu content until 2023.
It won’t quite be like Tamura or Shiibashi whose anime had ended long before their series did and they were both on the decline. Tamura took 2 years and Shiibashi only took one. Illegal Rare did well but was cancelled, and 5 years later he was largely forgotten for his next return. Fujimaki certainly still had a lot of momentum after Kuroko which is evident with RxL’s sales, it’s just the series itself was bad and it couldn’t keep anyone’s interest.
As far as how early they should return, I think it depends entirely on the state of their series when it ends. TPN and Kimetsu will both likely be ending at their peak with countless promotional material to come in the following years, so I do think they have a lot more time to play around with. With how much Beelzebub had declined when it finished, waiting 2 years was probably a death sentence in and of itself since HM was hardly good enough to gain an audience itself.
I do think it’s in the best interest of all mangaka to return asap though, there’s no reason not to take advantage of their status. Most aren’t Togashi’s or Matsui’s who can come back with even bigger successes, and every month they wait people will lose interest in them. We’ve seen too many of them flop and become one-hit wonders to think it’s worth taking a long break unless their health has really deteriorated. Though they can also kill their own fan base by writing something bad, so it’s a fine balance for sure.