Ownership is the precondition
If the agency owns the ad account, the analytics property, or the domain, then every number is filtered through a party with an interest in the answer. That is true of us as much as anyone else.
Registering everything to the client removes the conflict structurally rather than promising to behave well. It also means leaving costs you nothing but a password change.
Attribution has limits, and saying so is the honest part
Privacy changes, blocked tracking, and multi-device journeys mean no local business has perfect attribution. Anyone claiming otherwise is either mistaken or counting the same lead twice.
The workable approach is a small number of trustworthy signals: tracked calls, tracked forms, booked jobs, and revenue where your systems can supply it. Fewer numbers, each of which survives scrutiny.
Weekly beats monthly for a technical buyer
A month is long enough for a problem to become expensive and for the story to be rewritten around it. A week is short enough that the raw data is still fresh in everyone's mind.
It also makes the relationship falsifiable. If four weeks in a row show nothing moving, that is a real signal and it should be treated as one.