As with any psychiatric condition, the outcome is highly variable. By definition, a complete recovery should occur within six months of the ending of the stressful event or its consequences. Among the criteria that define this condition in the DSM-IV is a "significant impairment in social or occupational functioning." So, although the stressor itself might be relatively trivial, there can be a major impact on work performance. If the stressor persists or the consequences, this can become a chronic impairment.
The two most important factors are good previous psychological adjustment and the presence of a strong support system such as friends and family.