Listen, if you (as a team) have creative control, there is no such thing as an intractable problem; worst-case scenario is simply re-designing, omitting, and/or replacing the thing that's holding you up.
For well-organized and experienced teams, its no big deal at all.
UNLESS they are dealing with a publisher who adamantly demands features x, y, and z be implemented despite them being warned that this course of action will be unproductive, unnecessary or actively damaging to the project both in creative and logistical sense.
External producers have a lot of swing, but often in my experience not the creative chops to justify their influence and simply default (out of fear for their own jobs) to a position where they dogmatically defend the publisher's "interests" regardless of the developers warnings about the damage not changing tack is going to incur.
This is all it takes for a project to go to hell. I saw this depressingly often in my time, particularly when a publisher had very specific strategic plans for a project.