Final answer:
Layering is the type of guideline used in blunt cutting or to create a gradual increase in length.
Step-by-step explanation:
The type of guideline used in blunt cutting or to create a gradual increase in length is layering. Layering is a technique in which the hair is cut at different lengths to create the illusion of volume and movement. This can be achieved by cutting the hair using scissors or a razor. Unlike texturizing, which involves thinning out the hair to reduce bulk, layering adds texture and shape.