Test the convergence of the GP hyperparameters using IMRPhenomP
While I've demonstrated fairly clearly that the GP hyperparameters converge when using the NR waveforms, a more robust test would be to demonstrate that on a methodically generated grid of training waveforms the same effect takes place.
This might be prohibitively slow for the full 9-dimension(+) model, so a demonstration using a few parameters would be sensible in the first place, at least.