If you are in an area where seismicity is a concern, then you should understand the local seismic code requirements, as this will likely play a role in the wall design.
In seismic applications closer spacing of geogrid is recommended, maximum 16 in (40 cm). The top layer(s) of geogrid should also be extended, typically to roughly 90% or more of the wall height to satisfy design requirements. Using select/structural backfill will also reduce the effects of the dynamic loading.
For more information on seismic design and the effects on segmental retaining walls, see the (ref. BP, Chapter 11.1)