I created a 3D bin packing at work with similar basic heuristic you described, plus some additional flavor for testing some number of different combinations dur

I created a 3D bin packing at work with similar basic heuristic you described, plus some additional flavor for testing some number of different combinations during each iteration (and choosing the path that had best results up to that point). The interesting thing I found is that the simple heuristics work pretty well. I actually had to dial back the level of optimization because it took too long for the human packers to duplicate the packing correctly to be able to close the carton. I had to set it to a level that retained enough wasted space that allowed them quickly find their own solution, but knowing that for sure all of this stuff will fit into carton size X, because saving an extra few dollars in shipping didn't offset the labor dollars to pack it that way.