What are the pain points of financial audit?

I think the main pain point of expense audit for financial business is that, first of all, the expenses of business departments will be more complicated and more timely. However, if the financial affairs are audited one by one, the workload will be greater and the delay will be longer, which will cause unhappiness to the business department. In addition, the financial department will not participate in the business, and some actual expenses or some irregular invoices in the expenses will often be corrected one by one, but they will not be convincing.