Currently reading "Emperor of Rome" by Mary Beard where she argues that these parties are probably very exaggerated.

She argues that in the majority of unearthed royal palaces, the kitchens were very small and wouldn't allow to cook such complicated parties.

Besides, she argues, most stories of such big parties were written by sycophants needing royal approval, people anxious to show the importance they didn't have or political enemies with an interest in badmouthing previous emperors (mostly for Nero, Caligula and Elagabalus).