The answer is, it depends on the materials. Aluminum and vinyl products do not need regular maintenance. Most wood products, including plywood, do need regular painting or staining. Paint helps to protect against rotting and deterioration as a result of ultraviolet light. Paint also provides some mechanical protection against water passing over wood.
Some of the problems that arise with wooden soffits and fascia are-
simply not painting or staining the wood
using the wrong product
poor surface preparation
applications that are too thick or too thin
applying paint or stain when it's too cold or too wet
moisture moving out through the building
mechanical damage from trees and shrubs, for example
normal failure with age and exposure to weather
Blistering paint usually indicates moisture in the wood.
The implication of missing or failed paint or stain is deterioration of the wood.
Failures such as bare spots, checking, cracking, peeling and blistering should be noted. One of the easiest ways to evaluate a paint problem is to look for how widespread it is. In many cases, if it is age related, the paint will be failing in a roughly uniform pattern, or in areas exposed to more weathering. If there are unusual conditions, they are most often localized and the failures will be in certain areas. This rule isn't foolproof, but is helpful.