SZA is a descendent of Sade, in the tradition of black female vocalists who force the industry’s crude assembly line to move at their pace. Crucial to this maneuver is a refusal to apologize for the long interims between albums, so that privacy becomes an element of the smooth and squandering texture of this rare and sacred approach to fame. With that privacy and secretiveness often comes a level of tenderness that seizes upon the artists and supplies the music’s momentum.