Late Roman reliefs from Rome

[Theodosius the Great]

Off hand the only certain case that springs to mind of artists perhaps saving time is on the Arch of Constantine when earlier sculpture was reused and the heads of Marcus Aurelius and possibly Trajan too were remodeled to look like Constantine. There may well be other examples.

Indeed, I think the depiction of segmented armor on the Column of MA is noticeably simplified when compared to Trajan's. And, presumably, MA's column was erected in more prosperous times (i.e. before the 3rd century)

~Theo