Metallica can't afford to take time off.
The 'Enter Sandman' hitmakers - who earn a reported $90m from their tours - claim the music industry has changed so much, they are no longer able to take two years off work in between recording sessions.
Guitarist Kirk Hammett told Rolling Stone magazine: "The cycles of taking two years off don't exist anymore. We were able to do that because we had record royalties coming in consistently.
"Now you put out an album, and you have a windfall maybe once or twice but not the way it used to be - a cheque every three months."
Meanwhile, the band's drummer Lars Ulrich insists he has no plans to give up music, despite enjoying his role in TV movie 'Hemingway & Gelhorn', which aired in the US last night but will continue acting if he is offered projects that fit with his schedule.
He told USA Today newspaper: "Music is my main thing, so heading away to a place like, say, Iceland for a shoot would never work for me.
"But this was Phil [Kaufman, director], this was San Francisco, and this was six weeks total. No-brainer."