In my very cynical/pedantic view there is NO value in performing a Configuration Audit.
The value is BEING ABLE to perform it!
You set up your CM system/process to provide all the info/data etc to prove what you have is what you ought to have and to recreate whatever you need to recreate when/if you ever need to recreate it.
Once your CM system/process has been proven to be able to do all this there is no need to keep doing it.....
ie I DON'T "do" an Audit before a Product Release.... my CM system/process is set up to ensure that no Audit is required (but that if you did an Audit you would only report that everything was correct).
Possibly not a mainstream opinion but it is Friday afternoon!!
;-)