The Operations Dashboard layout takes up 100% of the screen, and there is no option to change this. While a single screen view reflects best practices/the ideal of dashboards, it is not always realistic. Sometimes you are working on behalf of a customer or you yourself want more metrics than can be viewed easily on a single screen. Or perhaps you are working on a laptop using ArcGIS online. At the very least, it would make it easier to edit the page if you had the option of scrolling down and seeing all the different maps or widgets you are thinking about including.