The original recommendation by Dr. Atkins was to break through a stall/allow weight loss for people who were so metabolically resistant that they didn't lose weight on induction.

I've found it useful if I've strayed a bit. Not usually stuff that high in carbs, but if I eat peanuts/nuts or cheese, sometimes I'll have an out of control appetite and start craving other stuff. So I'll go very heavy on cream, coconut etc., to really push the ketosis. Not necessarily that low in calorie. Anyways, next day my appetite's normal. Seems to help if I want to do more restricted fast, as well. So I sort of use it as a reset, but with more calories.