I don't know if procrastination has anything to do with it. It's easy to assume it does, but I can't be sure.I'd almost rather think he was procrastinating, than think that three years of constant work on one side-story can't produce more than what we've seen.
So, I should blame the breaking down of the interstice for the overuse of cartoony art, and misdirection of story? (Sorry if I'm sounding hostile, not my intent)
Sadly I feel they're actually aiming for a younger demographic at this point. Thus the degenerating shonen tendencies.
Middle of the Conviction arc, she's pleasuring herself to the thought of torture, after having found satisfaction burning people alive her whole life. Within a few chapters of joining Guts, (a week or two later?) she's risking her life to care for Casca. I can understand changing her, but there wasn't much transition, or time for developing a complete change of character.
Again, those are your opinions. Cartoony art is mostly limited to Puck and Isidro. The art has never been better. You can't expect a decently long series, much less one that has ran for 20+ years to maintain an art style. Every series goes through these changes. Misdirection of the plot?.......I'm not sure how to respond to that. The one who only knows the true direction of the plot is Miura, and as readers, we are allowed to critique it afterwards. I'm not sure what subplot you think he's wasting time on.
I can't disagree about what demo they're aiming for. The group that surrounds Guts now has done a lot to take away some of the dark atmosphere from the story for sure, but that could be by design. Only Miura knows. Remember, the series is still in a Seinen publication. "Shonen tendencies" is sort of a broad term, so not sure what you mean by it. People mistake comedic relief and goofy art for "shounen" sometimes, which couldn't be more wrong. Nothing about Berserk screams shounen to me.
IIRC there was a timeskip involved during Farnese's pursuit of Guts and then joining him thereafter. I don't know, I don't remember specifics.