Not really. It is based on restricting intake on 2 days out of 7 to around a quarter on normal daily intake, and in truth it does not matter much if you are a couple of hundred calories out.
2500 - 600 = 1900 deficit
2500 - 800 = 1700 deficit
"Normal" calorie counting diets might restrict to, say, 2000 giving only a 500 calorie deficit. Any error can negate much of the benefit. And that is done every day for months on end.
my pattern is 3 approx 200 calorie meals (no detailed counting) of protein, veg and fruit rich with no starchy carbs and no snacks. Other days i eat a completely normal diet, and if I fancy a Snickers, I have one. If social or family commitments get in the way of a diet day, I skip it without worry. No need to be paranoid about slipping off the calorie counting wagon!