LASAGNA Study Finds Top RAG Techniques Lose 41% of Their Gains When Combined, Not Additive

A new 450-configuration study released October 22 as LASAGNA shows three top retrieval techniques that each predict a +47% combined improvement deliver only +17% when stacked, a 63% shortfall and 41% median composition penalty across 17 combinations. The paper also finds retrieval quality and answer faithfulness are essentially uncorrelated (r=-0.01) and that small-corpus benchmark rankings don't predict production-scale performance.