How many times was Metallica's 1991 album remixed before its release?

Metallica's 1991 album was remixed three times before its release.

The repeated mixing was part of a demanding production process led by Bob Rock, James Hetfield, and Lars Ulrich. Metallica was known for pursuing exacting performances, and the band spent substantial time reviewing takes, selecting parts, and shaping the final sound.

The album's sessions were already unusually intensive. Rock asked the musicians to record more collaboratively and encouraged a stronger live feel, while the band worked through many takes and extensive overdubs. Those choices contributed to the record's polished, powerful sound.

The final result differed from the rawer and more aggressively thrash-oriented presentation associated with Metallica's earlier albums. Its broader, clearer production helped songs such as “Enter Sandman” and “Nothing Else Matters” reach listeners outside the traditional metal audience. The three remixes are therefore part of the album's production history, not three separate versions released as different studio albums.