Our school system has solved their efficiency problem by not only slowing gifted students but seemingly requiring them to stop all forward momentum. No acceleration and no 'enrichment' either. If you're done with an assignment alphabetize folders or tutor another student.
Same here. When full inclusion came six years ago, enrichment and in-class ability grouping were totally canceled in the elementary. Nothing above grade level can be offered. The old practice of going to a different class or grade to join an appropriate reading group was ended. If the student is done, s/he can read, draw, or navel gaze.
My own district replaced the SRA math series with Math Trailblazers 6 years ago, eliminating achievement grouping as part of the package. Since Trailblazers moves more slowly than SRA, this meant that the advanced students were doubly decelerated. They lost their accelerated curriculum and they were now learning less in the regular curriculum than the non-accelerated kids had learned in the past.
Recently the superintendent told the school board that Trailblazers is built for and depends upon heterogeneous grouping; if you're going to have Trailblazers you can't have grouping and if you're going to have grouping you can't have Trailblazers.
So naturally she's committed to Trailblazers.