Nowadays, the audit firms, including the Big 4 in the world adopt an top-down audit approach, so called 'Risk- based audit'. The deemed high risk areas (account) are the focus of the auditors ? Only minimal work will be done for the less-risky area.
However, the problem is auditors are the one who use the professional judgement to justify what area are risky. And, auditors might fail to identify the risky area of the business. Hence, no works were done for the risky area of the business!