The more uniform the orange, the easier it is. Remember you can always cut more, but you can’t uncut. As with any other skill, you’ll get better at this, and your speed will improve over time. Be careful your first times, as this fruit-in-hand method points the blade toward your supporting hand. The more you slide the knife, the less pressure you need to apply, which means less chance of an accident. However, slide it carefully so it doesn’t surprise you. I can remake with more detail if people would like.