We use Singapore Math (we homeschool).
My daughter has used it since Kindergarten, and is currently in 5th grade, last year she scored 96th percentile on the math section of her required standardized testing, so it must be a good “fad”.
It does outlive its usefulness when Algebra comes along. There the abstract advantage disappears. Our had it from K-5 and takes Algebra in 6th grade.