The industry has been in dire straits for a long time now and things have only gotten worse with more projects being greenlit. More projects in production at the same time, all with short deadlines. Why is that an issue? Because it spreads the available animators thin. Why are there so few animators? In large part due to the working conditions of the industry. Pay is abysmal, benefits are abysmal and production schedules are abysmal.
In-between animators only make $2-3 (USD) a drawing and can typically only do maybe 20 drawings a day. Rookie key animators make about $40 per cut (i.e. a single shot) and can typically do two cuts in a day. Forty years ago this was a different kind of problem because in the the 1960s-1990s television animation used much, much more simple character designs. Increasingly, since the latter half of the 1990s, television animation has demanded higher-and-higher quality animation more like the OVAs of old. Not only did the amount of lines and shading on character designs grow, so did the number of in-between drawings that episodes demanded. When Tezuka Osamu originally created his Tetsuwan Atom (Astro Boy) television anime in 1963 he intentionally kept the drawings around 1,500 per episode due to the lack of animators in 1960s Japan, the high number of episodes produced per year (52 episodes) and the lack of money (Tezuka was intentionally taking a hit on the series' production in hopes of making his profit through a media mix program: selling merchandise).
Toei Animation (Toei Douga, originally known for its high-quality animated films) began doing television animation as a result of the Tetsuwan Atom cartoon's success and decided to one-up the series by doing 3,000 drawings per episode! This number became something of a standard for the industry for quite a while. The number has fluctuated a bit over the years, with other studios gravitating closer to 4,000 drawings per episode on average. Pokemon (1997 through Best Wishes), however, stuck pretty closely to that 3,000 number. This is why the industry so historically relies on BANK animation (reusing animation), to create speed and action.
Modern television animation is just a completely different beast. Producers want to sell the next high-quality looking anime to overseas broadcasters but they very often don't understand the actual process of creating animation or the health of the industry. Pokemon was so very lucky for so long because despite it's relative and intentionally restrained production during the first four series it had the incredibly luck to have episodes being animated five months before they were to be broadcast. Iwane was already working on Diamond & Pearl Episode #171 when the Ginga Gang three-parter was originally airing, for example. Even recently, Mob Psycho 100 III was announced to have actually completed production THREE MONTHS before it was set to broadcast. That is insanely good, especially consindering how the Mob Psycho 100 III has always been treated as a prestigue work (the directing and animation for all three seasons is bonkers good). I'm not sure who within BONES is demanding such good production schedules—because even Boku no Hero Academia (My Hero Academia) is continually in production even during the hiatus months between seasons—but they have the attitudes that more studios need to have. "We'll give you your episodes but this is the amount of time we need to produce them."
Toei Animation had a really bad period during the 2010s where they were producing something like seven or eight weekly television episodes and various films, specials, commercials and video game cut scenes all at once. This was going on during the studio's major renovations, too, which made organizing even more hellish. Luckily, Toei Animation's new, state-of-the-art studio opened five years ago and they've been slowly fixing their production issues (that is, before COVID and the hacking occured). This article from Sakugabooru's kViN is really good:
https://blog.sakugabooru.com/2017/1...storic-studio-renewal-the-old-and-new-oizumi/
World Trigger Third Season and
Dragon Quest: Dai no Dai-Bouken (2020) had really good production schedules. If I remember correctly World Triger Season 3 was nearly finished or already finished when it began broadcast. As a result (and likely thanks to the recruiting by Series Director Hatano Morio) the season had quite a lot of good animation. Ota Akihiro had enough time to solo key animate
Season 3 Episode #2 and include an impressive amount of good, complex animation. Dragon Quest: Dai no Dai-Bouken (2020) had a health production schedule, also, with having 24 finished episodes before broadcast of the series began (although it appears that as they rapidly approach the final episode now the schedule has caught up).
The industry in general needs to stop producing so many projects at once if it's going to refuse to invest in paying living wages to staff and giving them non-abusive workplace environments (which includes proper scheduling). Otherwise you're going to get where Pokemon currently is: needing multiple recap episodes in a single cour (or any recap episodes at all).