Aisle be with you...
During some trials i was involved with some time ago, it proved speedier than normal, in a basic form, when operating a 2 aisle aircraft, to board ABC and HJK together, then centre block.
It could be broken down further by doing in sections working back from the rear. My recollection is that rows of 10-15 at a time was optimal, but depends on load factor. Full flight, smaller sections.