Another study suggests that LETRS training improves teacher knowledge but critically, does not translate to student achievement gains.
"Students’ third-grade reading achievement did not statistically differ for schools that adopted LETRS compared with other professional development experiences in any model, suggesting that LETRS was comparable to the other programs at improving third-grade reading achievement at the school level."
LETRS is a time- and $-intensive training initially embraced by Mississippi, so other states jumped for it like lemmings. But multiple studies have concluded that it doesn't translate to student gains. My suspicion: it's because it's too theory-heavy. Regardless, even Mississippi has moved away from it, and others should follow.