For generations, reading experts have told teachers that they had to teach students to read at their instructional levels. Teachers were admonished that if they taught children with books that were too easy, there would be nothing for the kids to learn. If they taught with books that were too hard, then the reading instruction would frustrate rather than improve.
In general, that kind of advice makes sense. Spend all the time you want teaching me my ABCs and it won’t likely improve my reading ability at my advanced level of performance.