I don't imagine that the sort of police constable who gets assigned to guarding schools is exactly the cream of the crop.
Some are, some are not. What I have found though is that the uniformed city police department cops do not do any actual investigation. In the UK even as a beat cop most of the crimes I was tasked to I investigated, with the minimum being a crime report, couple of statements and the Sgt telling me no further action. The deeper more complicated crimes would get sent off to CID by the Sgt/Insp and I would lose sight of them unless a DC decided he wanted me along for the ride as I had picked it up. I would deal with thefts, burglaries, and initial traffic accident evidential gathering and reporting.
What I have found here is that uniform cops mostly tend to cruise around issuing tickets for vehicle related offences. If a crime is reported they will attend and take some details, give you a crime number and bugger off. They immediately pass the crime report to the detectives department where it is evaluated for possible further investigation, uniform plays no direct role in investigation. The detectives investigate everything from petty crime, to serious crime, and traffic accidents, they don't even trust their uniforms with a traffic accident. Uniforms here are effectively no better than armed PCSO's with police powers.