If I understood the gist of the question, I'd prefer if as much of the world as possible was kept "constantly accessible" (i.e. you can move back and forth between areas) and I'd wish for the "chapter-specific gated content" to be kept to the bare minimum.
It's fine to have area where you can't access and/or go back at any moment for narrative/dramatic reasons, but I wouldn't want the progress of the campaign to be a linear list of areas that could be explored only in one specific order.
