Auditor rely on internal processes and controls?

"Where management is ultimately responsible for the financial performance of an organization and the reflection thereof in the financial statements, the external auditor needs to make sure that these financial statements do indeed paint a fair picture of the financial position of the organization. In the audit of these financial statements, the external auditor cannot audit each and every transaction. For example, checking whether or not the organization has applied the correct VAT percentage on each invoice is too cumbersome and inefficient. For many elements, the auditor will have to rely on the internal processes and controls. In addition to auditing key transactions, the auditor will therefore have to audit these processes and controls. With respect to the example on VAT, the audit can be a check on the administrative system and authorization as to changes. If an organization has a TCF with clearly defined processes, responsibilities and controls, this facilitates the task of the auditor."

Is this actually done in practice?