I've heard this too and thought it was brilliant. So James Cameron even repeated this and added constraints on the music with the second movie

    James Horner thought he’d have six weeks to write
    the musical score. Instead, he had three weeks,
    and had to write some parts overnight. The movie
    was behind schedule, not even finished being
    filmed (let alone edited) when Horner arrived in
    England. What’s more, the recording studio he’d
    been provided with was outmoded, not equipped to
    handle the synthesizers he wanted to use. Horner
    called the experience a “nightmare,” and ended up
    writing the climactic musical cue overnight.
    Coming away with the impression that a James
    Cameron film was too stressful and rushed, he
    figured he’d never work with the director again.
    And he didn’t ... until Cameron approached him for
    Titanic. (That rushed Aliens score earned Horner
    an Oscar nomination, by the way.)

It seems like there's a Machiavellian lesson there. There's a lot of great "making of" material on Aliens, which shows James Cameron being a genius on other aspects too.