Not many years ago, the Brits started a program for measuring the success of their jails and prisons by the rehabilitation rate—the reoffending rate—of those who had gone through it. That has proven hugely successful in challenging the institutions to make sure the right programs are delivered to the right people.
To quickly answer your question, targeting programs is exactly what you have to do with scarce resources, so that the right programs are given to the right people. Not all people can benefit from one particular program; they need to be challenged and focused. The Brits started a program doing that, and their reoffending rates are down.