To add multiple screens at once, simply go into the project you wish to add screens to and go into the 'Screens' tab on the left sidebar.

Now select 'Actions' then the ‘Add multiple screens’ option:

You can now start creating your screens by giving them a name and location, you can then add additional screens by pressing 'add screen'. Once you are happy with the amount of extra screens, press 'create all screens', this will generate all the new screens within your project.