MIAMI — With an increasing Miami Heat emphasis on 3-point shots, the approach still comes down to those who shoot them best also shooting them most often. Enter Tyler Herro and Duncan Robinson, each, in the view of coach Erik Spoelstra, a changed man. Already on display this preseason is a more rapid release from Herro. “That’s what all the great shooters do,” Spoelstra said, “is he continued to try to fine tune it, and that’s sped up his release.