alt Hacker NewsThe usual justification is that if you don't do at least a breadth-first literature review, you can get burned by missing a paper that already does substantially what you do in your work. I've heard of extreme case where it happens a week before someone goes to defend their dissertation!
Excuse my naivety, but isn't it good if the same results get proofed in slightly different ways? This is effectively a replication, but instead of just the appliance of the experiments, you also replicate the thought process by having a slightly different approach.