Do you have any insight into the results vs one of their peers who do not have this particular facet of the justice system?
Sweden, France and the UK don’t have that kind of system (e.g. Norway and Denmark have similar systems). They instead use longer sentences and do have higher crime rates but it’s going to be difficult to discern the impact from other factors.
At some point the distinction between longer sentences and preventive detention is semantics, but I’d say that preventive detention has the advantage of a) being less definitive, you often the court doesn’t impose it from the start but reserves the right to impose it later and if you’re behaving well you can dodge that bullet completely and b) inherently showing some mercy as it doesn’t impose prison conditions for the whole duration, making defiant non-cooperation less likely. Conditions aren’t always what they should be but once everything has been rebuilt etc. a preventive detention facility should look pretty much like a village with a fence around it, the only restrictions that are imposed on inmates are related to security (and side note security is managed quite differently in Germany too, compared to the US. Inmates tend to cook their own meals with their block neighbours (because getting used to routine) and yes they have knives. Figures that if you don’t treat people as animals they don’t act like animals).