Most effective: Large, flat areas similar to arms and legs.
Least effective: Curved areas cherish the underarms, and probably do cause significant trauma towards the face and also thin skinned areas.
If you cut mens' hair youll need hair clippers too. https://beachraven45.bloggersdelight.dk/2024/08/24/postpartum-hair-regrowth-by-using-the-effects/