The basis of this system is to assign an issue or subject categories to statutes and case law. Both of these types of systems require significant trained resources to implement properly. West spends considerable time and effort training their attorneys on the assignment of Key Numbers. In many courts it is not possible to devote the necessary legal resources to this task. I have only heard of a few courts where this has been successfully implemented.
Most courts are simply unable to make it work.
Similarly, some courts have tried to assign a case weight or a quantitative number to a case to reflect it's complexity or priority in the system. Prioritization has been very successful in the management of cases. In these systems litigants know the set of court rules they must follow to process the case. When litigants know the rules they play by them. But the assignment of a quantitative number which reflects the difficulty of a case has been less successful.