Most of the provisions and powers of the PCAOB have been well received, particularly due to audit failures like that of Enron, with the exception of mandatory rotation of auditing firms. Audit firm rotation is a provision that requires a company to change auditors at regular intervals in hopes of discouraging long-term relationships that could potentially interfere with an auditor's independence. Common opinions on this specific clause believe that the costs associated with this measure would exceed its benefits. Ultimately, there is no such business; they may look alike, but each is its own. The crucial objective of an audit is to obtain a truly independent opinion for all those who rely on the financial statements. For an auditor to become familiar with the company, a lot of research must be done and this takes time. According to a survey by the General Accounting Office, the average tenure of an auditor who is expected to interfere and increase quality and independence risk is twenty-two years. (GAO) With a mandatory rotation clause imposed, auditors would have great difficulty acquiring the knowledge necessary to attest to such impartiality