More inquiries is usually the wrong objective
A firm is limited by the hours of people who can do the work, which means the useful outcome is better clients rather than more of them.
Capacity in this business is qualified staff. If those hours are full, additional demand produces either declined work or work taken at the expense of existing clients.
That makes an ad account's job unusual. It should be attracting a narrow kind of client, at a price point the firm wants, in the areas where it is strongest.
Measures that reduce inquiry volume while improving fit are frequently correct, and they look like failure in every default report.
Publishing enough about your pricing model and your focus that unsuitable prospects rule themselves out is the cheapest version of this, and it happens before anybody spends a consultation on them.
The number worth tracking is not cost per lead. It is what a client acquired through the account is actually worth in recurring fees, and whether it is the kind of work you wanted.