When a band has a successful album, the usual plan is to release another one with a reasonably similar sound a couple years later to capitalize on the previous record’s success and keep the momentum going. Metallica has never done it that way. They work on their own timetable, and generally piss off a portion of their fan base with every new release, but garner legions of new fans in the process.
In 1993, Metallica released the box set ‘Live Shit: Binge & Purge,’ which consisted of three CDs and three VHS tapes (kids, ask your parents what those are).