The frequency of sharpening a katana depends on various factors, including the frequency of use, the condition of the blade, and personal preferences. Generally, a katana does not require frequent sharpening like kitchen knives or other everyday cutting tools.

The sharpness of a katana's edge can be maintained for an extended period if the sword is used and cared for properly. Here are some considerations regarding sharpening frequency:

1. Regular Maintenance: Routine maintenance practices such as cleaning, oiling, and proper storage can help preserve the edge of a katana. Regularly inspecting the blade for any signs of damage, rust, or dullness is important. If there are minor imperfections or dull spots, they can often be addressed through proper maintenance without the need for full sharpening.
2. Blade Condition: The condition of the blade plays a significant role in determining when sharpening is necessary. If the edge becomes chipped, dented, or significantly dulled due to heavy use or impact, it may require more immediate attention and sharpening.
3. Frequency of Use: The more frequently a katana is used for cutting or training, the more quickly its edge may wear down. If the katana is subjected to regular cutting exercises or rigorous training, it may benefit from more frequent sharpening compared to a sword primarily used for display or occasional use.
4. Individual Preference: Some sword enthusiasts or martial artists prefer their katana to have an extremely sharp edge and may choose to sharpen it more frequently to maintain that level of sharpness. Others may prefer a slightly blunter edge for durability or other purposes.

As a general guideline, it is recommended to have a katana sharpened by an experienced professional or a skilled sword polisher when it begins to show signs of significant dullness, damage, or when routine maintenance practices are insufficient to restore its cutting ability.

It's important to remember that sharpening a katana is a specialized skill and should be entrusted to experienced professionals who understand the intricacies of katana maintenance.

In summary, the frequency of sharpening a katana depends on factors such as usage, blade condition, and personal preference. Routine maintenance, proper care, and periodic professional assessment can help determine when sharpening is necessary to maintain the katana's cutting ability.