Need clarification of "the boundary of the model". Maximizing the datum to 3D extents does not necessarily confine the datum to the Crop Boundary of the currently active view - as the last graphic implies. It seems to maximize the datum to the furthest extent of any element in any view, visible or not. This may be well beyond the Crop Boundaries.
Is there another explanation?
(the link to the first graphic appears to be broken)