The OneDrive Problem Caused by Deleting User Accounts

On the surface, the work to delete OneDrive for Business accounts seems straightforward because Microsoft provides a 30-day deletion period to review contents and uses an automatic delegation process to assign control over the account to the deleted user’s manager. But given the number of applications that store data in OneDrive for Business, can anyone perform an end-to-end review of what’s in the account in a reasonable time?