Sometimes you just want to wait before you release a couple of chapters or you might be creating several branches for a game mode story. When you are done then you have to go back and click the page, click edit story, and then click publish for each chapter you where holding back which can get a little tedious. What if you had a button on the story map that allowed you to publish all unpublished chapters at once.
It would risk publishing unfinished things you forgot about. I think a better way would be to to be able to publish a draft from the story map using the small button at the end of the line with the three points or an option for delayed publishing so that all get out in a sequence at about the same time. Or a way when publishing a draft to publish all chapters above it in the branch. You write 5 drafts, go publish the last one and instead of a bug all of them are getting out. Or a publishing mode where you can toggle on or off chapters on the story map and they would get either published or returned to draft mode once you get out of the publishing mode.
Another disadvantage of publishing them all at once is you lose the increased exposure from being in 'recently updated stories' for a longer period of time than if you publish one every few hours/day. However, I do like the possibility of having the option.
Just wanted to note I'm tossing a vote in for this. I just published like 50 saved chapters on a game mode story, including a lot of link chapters that needed only minimal review, and it would be a god-send to have a "publish all" button. The suggestion by TheDespaxas above is even better, but I would gladly accept a button to publish everything that is saved but not yet published. It'd be a big help on single-author game mode stories where the author has some discipline to be aware that all the unpublished chapters are indeed things the author wants to publish. Basically, any way besides having to click in to edit each and every individual chapter on the story map and hit to publish separately would be a big time-saver and greatly appreciated.