We've discussed often how Everyday Math doesn't build to mastery, but spirals through the same topics year after year at a shallow level so students never get enough practice. Teachers and parents are told to "trust the spiral"--if the student doesn't learn the concept this time, they'll learn it next time.
But no one tells the students that.
I hear stories now of children in tears of frustration in first and second grade because they are being asked to "learn" concepts without enough background. These children aren't able to blithely say "oh well". They are crushed at their obvious failure. They feel stupid. They feel miserable. They are learning to hate math and their inability to do it. The assignments aren't meant to be mastered yet, according to the adults. But the spiral won't stop their students' feelings of awfulness.
We can't teach children that math is coherent, reasonable, and learnable with effort this way. Students need to be given concepts of slowly-increasing difficulty, designed so hard work leads to success. It's not just we've robbed them by giving too little chance to build up to complexity. Giving "tastes" of concepts they aren't ready for undermines the "effort is good" message and reinforces you're math-smart or math-dumb, and there's nothing you can do about it.