Media audits are of course only a part of the total marcom pie. Normally these audits are only performed on offline media and more specifically only market conformity of buying results by media agencies. In addition, a lot of conclusions and or recommendations are not implemented in practice.
These do not cover digital media, creative agencies, PR, sponsoring, folders, POP, printing, distribution content suppliers, DTP amongst others.
Moreover, they do not cover hidden financial flows or the remuneration of your offline media agency. These audits cover a just small percentage of what MiM is checking.