Final answer:
Shears should be sharpened based on the amount of use and the type of shears. Professional hairstylists should sharpen their shears every 500-700 haircuts or every 6-12 months. Personal shears used at home can be sharpened once a year or whenever they feel dull.
Step-by-step explanation:
The frequency of sharpening shears depends on the amount of use they receive and the type of shears being used. For professional hairstylists, it is recommended to sharpen shears every 500-700 haircuts or every 6-12 months, depending on the quality of the shears and the frequency of use. For personal shears used at home, it is generally sufficient to sharpen them once a year or whenever they start to feel dull.