Maybe to help clarify for the OP- If you had them all in one conduit (not common, but can be done) you need just one EGC sized per Table 250.122. If you did it in 2 or more conduits each would need an EGC in each conduit based on Table 250.122 at the full amount of the overcurrent device. In other words, if you have 2 conduits, you can't divide by 2 for the EGC.