Concur can be configured by each end-user organization to alter the approval and audit flows. Most likely, timing for these is going to be more dependent on internal resources of the organization. For example, my boss gets a notice when I submit an expense report. He can either "look at/approve" it immediately, or next week. Which will be different then someone else's boss. And similarly, our Finance team has someone that looks at them for adherence to travel/expense policy. How quickly they perform that task is different than other organizations.

I am not aware of any "audit" done by Concur itself, perhaps outside of automated flags. But again, these flags are controlled by the organization.

Concur is just the system (software) being used.