Workgroup approvals have a field for approval by (any member of a) workgroup or, leave the workgroup blank and setup approval by one (single) employee. When an employee-turnover event occurs 'someone' has to remember all the places where that employee MAY have been involved in workflow approvals.
However if an approval was tied to a POSITION then no maintenance would be required. Suggest a field called ReportsTo/ApprovedBy could be added to the User ID and default into the Employee ID and then used by Approval Workflow as part of the way to automate the above idea.
AP clerk ReportsTo/ApprovedBy the AP Manager. Approval required by AP Manager (not Don Jones). School of Arts purchases over $10,000 approval ReportsTo/ApprovedBy Dean of Faculty (not Mary Flores).
In general I believe this process should start at the USER and/or EMPLOYEE level. Employee Nancy Morris is an AR Clerk. The AR Clerk ReportsTo/ApprovedBy the AR Manager. The AR Manager ReportsTo/ApprovedBy the Controller, the Controller ReportsTo/ApprovedBy the CFO (POSITION).