High Imperial Roman army vs Late Roman army

[Frank]

Romans never again tried to conquer Magna Germania after that defeat. After Teutoburg Forest, Romans applied a purely defensive strategy, defending their territory, not attempting to conquer areas east of the Rhine. They also built border fortifications systems (Limes Germanicus, Limes Raeticus).

Actually, nothing changed after the Clades Variana. Tiberius changed his mind after Germanicus' campaign failed, or at least had not the expected success. A change in military strategy can not be seen before Domitian reorganized border defense after he definately conquered territory east of the Rhine.