Local presence, well-known in the community and always available.
Centralization and big units are not good ideas – even if they in theory can save money and be more efficient.
The police must be present and available at all times. Obviously they cannot be everywhere, but they must be nearby and easy to reach in order to prevent crime and create a sense of security. So when centralizing the police units, gathering the policemen togehter at central police stations there is less crime prevention and less sense of security.
It is the same with doctors, ambulances and emergency rooms. If they are not nearby and available then there is no sense of safety – regardless the objective efficiency of centralized hospitals.
Feel free to leave constructive input and examples of the need of local presence below.