The practice of folding steel during the forging process of samurai swords, known as "hada-gane," varied among different swordsmiths and eras. While the exact number of times swords were folded cannot be definitively stated, it is a common misconception that samurai swords were folded hundreds or thousands of times.

The folding process in swordmaking was primarily intended to homogenize the steel, remove impurities, and distribute carbon evenly throughout the blade. Folding also helped to create the distinct grain patterns seen in traditional Japanese swords.

Historically, it is believed that Japanese swordsmiths typically folded the steel between 8 to 16 times during the forging process. Some exceptional blades may have undergone more folding, but it is unlikely that they would have been folded excessively beyond practicality.

It's worth noting that the folding process was just one step in the overall swordmaking process. Other factors such as the choice of steel, heat treatment, and meticulous craftsmanship were also critical in determining the final quality and performance of the sword.

While the folding technique played a role in the creation of traditional Japanese swords, it is not the sole determinant of a sword's quality. Factors such as the skill of the swordsmith, the steel composition, heat treatment, and overall craftsmanship have a significant impact on the sword's performance, strength, and durability.