In the screen summary, this screen will list all input and the output screens of the project. Next to each input screen and output screen will be a list of use cases that are associated with that screen.
There is an additional option to distribute the effort in percentage terms across the various listed input and output screens. For example, the input screen for a use case may hold most of the functionality and the output screen is simply a landing page. For this, you may want to distribute the effort eighty percent for the input screen and twenty percent for the output screen.
The benefit of distributing the effort amongst your input and output screens is that it helps further define the use case and adds analysis to your effort so that a project stakeholder may take the document and see where the effort is heavy and where the effort is light to make any necessary changes such as redistributing the effort or even remove some effort from a particular screen.