lol. deep means at least 7mm in my estimation, 1/3 of an inch for you imperialists.
another good tip for knifing is to keep them sharp, blunt knives are more likely to get stuck and then suddenly move as you cut, which is far more likely to lead to an injury than a sharp knife that steadily slices.
plus, it's meditative sharpening knives. diamond sharpeners make it pretty easy, just gotta get used to the right angle and strokes.
