We set a marketing budget once and never checked what it was actually buying
A shop decides to spend a set dollar amount a month on Google ads and lead services at the start of the year and rarely revisits it once the calls start coming in. Nobody tracks what that spend cost per booked call, or whether the calls it generated were profitable jobs or low-ticket service calls that barely covered the tech's time.
A working budget tracks marketing spend against booked calls and average ticket every month, so you can see whether a dollar spent on leads in June is producing the same return as a dollar spent in November.
Shops that never check cost per booked call commonly keep paying for a lead source that costs 150 dollars a call while a cheaper source sitting unused would produce the same booking for 60 dollars, a gap that adds up to thousands of wasted marketing dollars a year.