Final answer:
The double-rod wrap technique is effective on short or strongly textured hair, designed to create well-defined curls and added volume in hairstyles that require extra control.
Step-by-step explanation:
The double-rod wrap technique is especially effective on hair that is short or has a strong texture. This technique involves using two perm rods instead of one while wrapping a hair section. By doing this, it allows for a stronger and more defined curl, particularly on hair that may be difficult to style or that doesn't hold a curl well with a single rod. This technique can create more volume and support in the hairstyle, making it a preferred choice for those with shorter or heavily textured hair where extra control and definition are desired.