Ray tracing, and more generally, graphics operations taking place in a 3-D scene, involve a plurality of constituent graphics operations. Scheduling of graphics operations for concurrent execution on a computer may increase throughput. In aspects herein, constituent graphics operations are scheduled in groups, having members selected according to disclosed aspects. Processing for specific graphics operations in a group can be deferred if all the operations in the group cannot be further tested concurrently. Graphics operations that have been deferred are recombined into two or more different groups and ultimately complete processing, through a required number of iterations of such process. In one application, the performance of the graphics operations perform a search in which respective 1:1 matches between different types of geometric shapes involved in the 3-D scene are identified. For example, closest intersections between rays and scene geometry can be identified by processing scheduled according to disclosed aspects.