If you are concerned about your staff switching positions or roles, or leaving the organization, you may want to consider creating an alias user for a particular role.

For example, let's say you have an I.T. Manager called Robert Smith, their user ID being rsmith. You could set various articles to have the approver set to "rsmith", but then what happens if that employee is promoted, or if they leave?

To separate staff roles from actual users, you can create alias users. These are regular users on the Users tab, but you give them the name of the role. For example you would create a user called "ITManager". You would then use the Delegate action on that user to delegate their assignments to the specific user who has the role of IT Manager, in this case rsmith.

Then you would set the approver of relevant articles to be ITManager, not rsmith. 

Now, whenever a change needs to be reviewed, it will go to ITManager but will automatically be delegated to the user who is filling that role: rsmith.

If Robert then gets promoted or leaves, you simply go to the ITManager user (as admin) and delegate it to a different user, and all existing assignments will be switched over to the new user.

This can be a better way to organize your approvers in a more scalable and manageable way.