The closest to a "scientific" approach was one done by Brian from BHB last year. He had 3 sets of hatchlings. Once set got the "standard" feeding regimen. And by "standard" it's what he does. I think that was prey just slighly wider than the snake every 4-5 days. His other groups were:

1) Feed smallers meals more often (3 days).
2) Feed slightly larger less often. (6-7 days).

If I recall correctly, the Larger Less Often group won out for growth. With the Smaller More Often group being the least successful.

Keep in mind this was for hatchlings who have higher metabolisms. I don't know of any type of feeding experiments for adults.