"This Is Really Confusing! I've Sat in on Audit Planning

Essay

"This is really confusing! I've sat in on audit planning meetings for three different clients so far,and each one has gone differently.I've been responsible for the sales section each time.Sure the risks are all different,but in the first one I'm supposed to do flowcharts and detailed narrative for the sales systems,in the second one I'm supposed to use the firm's computerized system to answer detailed questions,and in the last one the partner only wants a brief description of the system in narrative form - no more than one page,he said."
Required:
Explain why it may be necessary to do different types of documentation to support an understanding of internal controls in the context of risks and evidence mix.