Metallica’s 1991 album recording sessions were conducted over approximately eight months.
The sessions began on October 6, 1990, and ended on June 16, 1991, at One on One Recording Studios in Los Angeles. The extended schedule reflected the band’s detailed work on performances, arrangements, and production.
Producer Bob Rock played a central role in the process, working with James Hetfield and Lars Ulrich as the band developed the album’s more controlled and polished sound. The sessions were frequently described as difficult because the group and producer challenged one another.
Eight months refers to the recording span, not the period from the album’s release to its first anniversary. The album itself came out on August 12, 1991, after the recording had already been completed.