Will all the objects used in the workflow will not be checked in or is it just the workflow which will not be checked in?
The objects that will be left in the checked out state are:
- the workflow,
- the new objects (i.e. they were not present in the Prod repository before the import from Dev/Test),
- the modified objects (i.e. they were present in the Prod repository but were overwritten because you chose the Replace option).
I have to go one by one to check in the objects
You don't have to check in every individual object - in Repository Manager open the Versioning menu and choose the Find Checkouts... option. All the checked out objects will be listed - you can select them and check in all of them at once.