The average is less than 50%, and some groups are handling less than a quarter of requests on time (there is a caveat that the Police Information Request Tool does not necessarily handle extensions properly, but that's their data).
How are things this bad? The usual police problems: poor leadership, no ownership, poor training and institutional culture, and no proper performance reporting - meaning that Ombudsman's complaints and adverse media reports are their only feedback mechanism. They correctly pick up that the sign-out process is a common blockage and responsible for many delays (which they blame on "capacity of those doing the sign-outs, [and] relative priority of OIAs to other work") - but they completely miss the underlying driver of increased information control freakery from police command. So any good work done by people lower down the chain gets destroyed by those at the top wanting to cover their arse against the possibility of bad headlines.
There's a host of recommendations, and the questions now is whether the police listen, or just continue to suck. Given their past performance and institutional resistance to change, my money is on the latter.