The short answer is … they should receive phonemic awareness instruction until they have automatic access to the phoneme s in words. If your students are already sounding out words and spelling words successfully, they’ve probably had enough instruction. If they’re struggling with those things consistently, then they probably still need more phonemic awareness work.
While some researchers in the field are concerned that phonemic awareness instruction receives a disproportionate amount of time in kindergarten and first grade, there is no set rule about it. Flexibility is especially important for struggling readers.
For most students who are on target for word recognition by the end of first grade, the more automatized phonemic skills (phoneme deletion and substitution) will naturally develop via reading. These readers generally do not need further phonemic awareness instruction after first grade.
Unfortunately, for the large portion of children who are not typically developing (a percentage that’s hard to estimate), phonemic awareness does not become automatized and orthographic mapping does not become efficient. These students need continued phonemic awareness instruction.
Assessing students regularly is the best way to know whether students need more phonemic awareness work — and what skills they need to work on. We have a short phonemic awareness skills assessment you can use for this purpose.