Lightning mode is a user setting for completing multiple checklists quickly. The switch can be found on the Settings tab.
When enabled, the app will immediately start another checklist when a checklist is completed. It will be the same checklist, and mainly only useful when the checklist is configured to use Location Tags via the Tree Manager.
When starting a new checklist through lightning mode, the selection of the location tag is moved back one level. The user can quickly pick at that level again, or change that information as when Starting a Checklist. Pressing the back button in the top box will return to the home screen, and the checklist will not be started.