In 0fba72a I tried to address this by adding a static method that would load saved run from disk.

This differs from the convention introduced in the Matrix and Vector classes where

vector = om.Vector(path='path/to/vector.npy')
matrix = om.Matrix(path='path/to/matrix.npy')

will load these objects from file.

I guess my question is if it is desirable to use the same convention for the entire package?

If the answer above is yes, then one will probably need to remove the ensemble and trapezoid attributes in the Extractor class. Removing these attributes should be simple as these are only used in Extractor.extract_from() and functions called by this method. I will add the change to the draft.