It's required in the PPL syllabus here.
Students need to be taught how to do it properly, and know about the correct configuration; rather than giving it a try on their own after reading about it in their Trevor Thom!!
However IMHO it's more important to be able to do a correct approach without having to resort to sideslipping, which can get the unwary into trouble with a slow and out of balance configuration which could lead to a spin at low level.