Is Security Context Value assignment required if Data Set is All Values ?

Summary:

We see a conflict between steps in Doc ID 2735319.1 and common security features of Oracle cloud. Any explanations ?

Content (required):

As per Oracle doc "No Business Unit Available In List of Values (LOV) In Search Leases For Lease Accounting (Doc ID 2735319.1)", step 5 we need to give Data Set as "All values", when creating Lease Accounting job role. If we do that,

a) do we need to further assign a security context value for the Lease Accounting job role to the user (step 8 in the document) ?

b) further, if we want to restrict the access of a user per business unit explicitly assigned, do we still need to give Data Set as "All values" when creating the job role (as mentioned in step 5 of the document)