If you don't the app may crash at runtime with no clear error message. We have learnt these the hard way!
Ensure the application name in visual studio does not have any space in it.
The Android application name must start with a lower case letter.
When handing the files under App.UI\Resources the framework will convert every hyphen character (-) to underscore (_). So ensure you don't have 2 files of which names only vary in that.