There is no hard and fast rule; the tests you perform should be
sufficient to establish whether a trader’s business and
declarations are credible. Examples of the types of credibility
tests available are provided from HMASCR3000 onwards. As you become
more experienced in credibility testing you may design tests not
included in this guide.
The most appropriate test to adopt will depend on what information you have available at a particular test stage and the answers you are seeking.
During a standard assurance event the majority of tests will be either predictive or trend based.