Exact time is not a service level. It is inventory, and most operations give it away without noticing.
Why it matters
A single exact-time commitment in the middle of a route splits the day in two: everything before has to finish in time, everything after starts from there. Two of them on the same route, in different parts of the territory, can cost an hour of driving that no planner can recover.
Used sparingly, it is a genuine advantage — there are accounts where it wins the business. Used as the default, it quietly removes the flexibility that makes every other appointment affordable.
How you notice it slipping
Nobody can say what share of appointments carry an exact time. When measured, it turns out to differ wildly between the people taking the bookings, which means it is a habit rather than a policy.
What to do
Require a reason for each one and review the reasons weekly. Set an expectation for the share — many operations run healthily in the single digits — and let the booking team see where they sit. The number moves quickly once it is visible, because almost nobody is defending it deliberately.