The same thing happened when we were working on Leopard under Bertrand. Because the developer toolchain switched to Objective C 2.0 with garbage collection enabled, the OS was unusable for development for months at a time.

Development took twice as long as planned, the release was fairly bloated, and required 2 or 3 updates in the first month or two.

When Craig took over he introduced a sprint model so that there were periodic relatively stable releases. If something wasn't ready and there were still sprints left, you could push it back.

But it sounds like there has been milestone creep causing those sprints to either become more heavy or less missable. And I'm guessing the consequences for missing a sprint are more career limiting than they were when the methodology was still new.

It's like Rich Hickey said, we're smarter than runners, we just fire a new starting pistol every 100 yards and call it a new sprint: https://www.youtube.com/watch?v=zPT-DuG0UjU