Can *UANISOHYPER_STRAIN subroutine be calibrated with material constants that govern the long-term material response?

Am I right in saying that anisotropic hyperelastic solids can only be based on the instantaneous material response?

Is it possible to use parameters from tensile tests at low strain-rates? (i.e. the long-term material response) 

This would be quite convenient for implementing simple viscoelasticity.