These are great questions.
Before I answer your specific questions, it’s key to understand the following concepts:
- See here to understand how to enable Case Sharing correctly.
- Each case has an attribute called Owner.
- When Case Sharing is NOT enabled, and a user creates a case: Owner is set to the User
- When Case Sharing is enabled, and a user creates a case: Owner is set to the Group [the case sharing group the user belongs to]
Moving on to your questions:
What will happen if the group was set to case sharing while the application wasn’t?
In this situation, when a user creates a case, the Owner is set to the User.
What will happen if the group was NOT set to case sharing while the application was?
In this situation, you will see an error in the app, and it will prevent the user from submitting data.
If the case sharing feature is off in the setting of the group what is the benefit of having a group of mobile workers whom not sharing their data?
[If I understand your question correctly] Groups are also used for Reporting. If you have supervisors or staff that will monitor collected data, they may need to only see data of a subset of your Mobile Workers. For example, if you have field workers that encompass different catchment areas, you may want to organize Mobile Workers based on geographic region or other categories, including health center, mobile health unit or hospital, etc. See here for more info.
Does this help?