Sure but that’s the point, all GPUs work on the principle of warps/wavefronts, I.E. (in the case of AMD, I think Nvidia’s work groups are smaller but that isn’t totally relevant) all threads are grouped into 64 grouped bunches. If you’re shooting off rays in random directions on will go left, taking the entire warp with it, hit something, return/ Then the entire warp will wait until the next ray goes off to the right, hits something returns what it hit.
But if you can group rays together, as in they all go left, then they’re all (potentially) going to hit the same thing, and return the same thing, or at least a lot more of them will. You’ll thus, in theory, be vastly reducing cost of multiple rays. The ideal would be to use UE4s tiled lighting (where each tile is 8x8 pixels to match the above warp/wavefront structure) to bin ray bundles. You’d isolate pixel clusters (actually clustered lighting would be much better for ) close enough to each other to matter, shoot rays roughly parallel to each other (as above) from these clusters, and you could theoretically use a single warp/wavefront to shoot an entire bundle of rays. Parallelized raytracing, much, much faster than the random rays done now and more in line with how GPUs work!
But you’d need to be quite clever to get it working right of course. Each pixel is going to have a different normal, and you’d have to figure out how to cover the entire hemisphere while doing near parallel bundles at the same time.