The only thing that fell flat was Frank's Saw bit.
I thought in a way that worked because
of course that's Frank's go to horror situation video reference to use. Like the rest of the gang, it's all outdated and they can't pull it off.
I agree with you that they're getting dense and I think that plays a role in people disliking/liking stuff. Where before they might have a specific joke prepared for Charlie, now they run through one for Mac, one for Charlie, one for Frank, one for Dee and leave em all in for the same segment. And some combo of the four hits for you, or none of them do.
I've spotted a few scenes where I think they're actually taking two completely different cuts and combining them as if they were an extension of one another. Like Dennis' talking about all the ways he'd punish Dee when they visit the psychiatrist. Like I could see them having four ideas, and then also ad-libbing a few, and then realizing they could splice the two together into one really nasty but funny Dennis is a psychopath monologue. Or then refilming the scene with that as the dialogue now. (I know they've said they do that with some of the ad-libbing.)