Nails should be filed in which direction?

Filing nails from corner to center is optimal as it helps maintain the natural shape of the nail while preventing splits and breaks. This technique allows for controlled filing, ensuring that the edges are smoothed out without putting excessive pressure on any one side, which could lead to nail damage or unwanted shapes.

When filing in this manner, you also minimize the risk of creating uneven lengths, as starting from the corners and working toward the center allows you to achieve a more uniform result. This method also helps to avoid filing too aggressively, reducing the likelihood of causing the nails to weaken.

Filing nail edges at an angle can increase the risk of snagging or breaking, which is why this approach is promoted over side-to-side or up-and-down techniques, as they can lead to uneven shapes and potential damage.