I can certainly answer the question in terms of why we don't and why it may not be applicable.
If you consider again the threshold for remand for assessment, it's not exactly a hard test. There are soft criteria that a judge has to consider to determine whether it meets the criteria of a serious personal injury offence. The base threshold for that--where you would start--would be at least a 10-year possible sentence. You'd potentially have to look at every single individual who was convicted of that prerequisite offence. Then you'd have to look at each and every decision of the sentencing court to determine whether in the court's mind.... And you'd have to step into the shoes of the court, which is virtually impossible. You'd have to go through the transcripts from over five years, meaning for probably over a hundred thousand cases. The amount of resources it would take to do that would probably not really justify the exercise.
Overall, I would suggest, as has been said many times by the Supreme Court of Canada, that the dangerous offender application is to be used in the rarest of circumstances for those offenders who show no prospect of rehabilitation, for the purpose of protection of society. Because of that, the number of actual applications is, by its nature, going to be very small relative to the total number of offenders before the court. In the vast majority of cases, the sentencing scheme provided for in the Criminal Code is satisfactory to manage the risk posed by most offenders. In the rare instance where the sentencing scheme is not, the dangerous offender proceedings are there to provide for an alternative sentence--the indeterminate sentence--to ensure public safety.
Again, while I can see why you're asking the question, the type of review you're asking about would probably be somewhat impractical and really would not assist in determining whether there's an appropriate policy in place.