There is usually a set of common insider reasons that are reused amongst your insiders. In order to make operations more streamlined you can set up your own insider reasons to be used in the service.
Add reasons by start typing and ending with enter:
Remember to click save when done.
When adding list members to a project your insider reason options will be available in a dropdown to be selected:
If you want the same reason for multiple insiders remember that you can use the "copy first row to all" button: