Which type of filing motion should be avoided for proper nail shaping?

Filing back-and-forth is a technique that should be avoided for proper nail shaping because it can lead to weakening and damage of the nails. This sawing motion creates friction and can cause the layers of the nail to split or peel, resulting in weaker nails over time.

In contrast, filing in one direction is a gentler method that promotes healthier nails and prevents these issues. Following the natural shape of the nail allows for a more aesthetically pleasing finish without compromising the integrity of the nail structure. Additionally, using gentle pressure ensures that the nails are not subjected to undue stress during the shaping process, further preserving their strength and durability. Overall, the proper filing technique is essential to maintain nail health while achieving the desired shape.