I just read The Great Cleric because it was on catch-up, and it might be the most impressive example of falling off a cliff only to climb out of the hole I've personally encountered. It starts off as nothing special, but there are some fun characters and mysteries in the second and third volumes (the first is entirely a training arc), but in the fourth and fifth volumes literally every character besides the MC is ditched along with much of the plot up to that point in favour of a huge new cast that is barely introduced and random political shenanigans. The new characters are soooo boring and one-note. The earlier volumes introduce an obvious love interest and her friends who are actually interesting to have in the party, only for her to become irrelevant for multiple volumes for...no reason. And when this second arc is done, the new cast introduced to replace the old one is almost entirely left behind in favour of a mix of the old and new. I only pushed through to the end of volume 5 because it was free, though the finale was the start of a comeback.
It seems like the author realized his mistake at some point though because around volume 7 all the original characters and the permanent keeps from the second batch keep being relevant at regular intervals, but what saves the series is that the MC becomes a leader that is fun to watch in a crisis. Volumes 7 to 10 are easily the best of the series so far, and far better than the first three, but getting there is a tough sell.
On a positive note, it is the only isekai adventure series I've read so far where most of the regular cast is male. And while there are harem indications (I imagine the epilogue will consist in marrying at least 6 women), there are no harem antics, and one of the girls is clearly in focus.
I would also like to report that Full Clearing Another World Under a Goddess with Zero Believers is one of the rare consistent quality series, and to some extent it gets better as it goes. It's not nearly as good as Bookworm though, but it is good fun.
