Viscoelastic behavior of geosynthetics in MSB systems

Structural and geotechnical engineers who are used to working with MSB wall materials such as concrete and steel which are not viscoelastic by nature tend to view geosynthetic reinforcements, because they are viscoelastic by nature, with caution. However, is creep really a serious problem for geosynthetic MSB systems? Regarding longterm strength design, the reduction factor for creep is typically the largest reduction factor applied. However, based on performance and the nature of in-soil geosynthetic creep, does the reduction factor need to be so large? If, based on performance, creep is really not that big of a problem, what can be done to make creep assessment and design procedures more realistic?