Concise answer
Consistent broad-spectrum sun protection can reduce an important trigger, but it cannot guarantee that melasma or other pigmentation will never recur. Heat, visible light, hormones and inflammation may also matter.
Protection works best as a daily habit that includes adequate application, reapplication when relevant and practical shade or clothing.
It supports treatment but does not replace identifying the pigment pattern or controlling irritation.
When evaluation may help
Review is useful when pigment keeps returning despite regular protection or when products cause stinging, acne or visible irritation.