As businesses have grown more complex and sophisticated, and the costs of labour have risen, automated systems and processes have necessarily become much more prevalent. A well-run business will have its own systems and controls in place to operate efficiently, safeguard its assets, and to provide reasonable assurance that its transactions are properly reported and that its financial statements are complete and accurate. The auditors assess the effectiveness of these controls in preventing and mitigating the possible risk of material misstatement in those areas where the auditor plans to use such controls to adjust the nature, timing and extent of their testing. If they believe the controls are effective. And they have tested that they operated reliably throughout the year, then the level of substantive audit evidence needed to give an opinion may be reduced. Even if the controls are reliable, varying degrees of substantive audit evidence will still always need to be gathered.