Final answer:
Properly fitted shears should allow the thumb hole to rest comfortably at the point where the handles meet the body of the shears, ensuring both control and prevention of strain.
Step-by-step explanation:
When shears are properly fitted, the thumb hole should rest at the point where you have full control over the shears without having to overly bend your thumb. This typically means that the thumb hole rests at the intersection where the handles of the shears meet the body. It is essential that the shears fit comfortably to ensure precision in cutting and to prevent repetitive strain injuries.