Approaching Automation: Should Core Functionalities Be Automated Across All Modules or Individually?

Hello everyone,

In our project, we have both core functionalities that are shared across multiple modules and module-specific functionalities.
For instance, access levels to various module pages are determined by user roles.
Bank transfers and withdrawals share the same access level functionality, but each also has its own distinct processes and features.

Now, Iā€™m looking for advice on how to approach automation for these functionalities.

Should we:
a. Automate core functionalities across all modules together, or
b. Automate core functionalities individually, focusing on each module separately?

Your suggestions on the best way to proceed would be greatly appreciated!