There are crudely carved inscriptions on some that are very obviously not by whoever did the exquisite original work of making the boxes. Tagging work that was already ancient was a favorite activity of dynastic Egyptians. Ramesses II was especially fond of the practice, but for some reason not even he tagged pyramids.
Some later generation of Egyptology will acknowledge that a cartouche carved into a piece of stonework only fixes a lower bound on its age, and cannot by itself identify who made it. You can feel with your fingertips the difference between the quality of the work that went into the tagging, vs the original work. The oldest and best work had originally no inscriptions, although they were easily added.
Somehow the methods for doing the very best stone work were lost, early on. Early pillars were made all in one piece, later were stacked. It is hard to believe later generations were always just too impatient to bother doing top quality work.