\version "2.16.0"

melody = \new Staff \relative c' {
  \repeat unfold 16 ees8
  \bar "|."
}

chordsA = \chordmode {
    \repeat unfold 2 {
        ees8:7
        q q q q q 
        bes8:7
        q
    }
} % chordsA

chordsB = \chordmode {
    \repeat unfold 2 {
        ees8:7
        \override ChordName #'stencil = ##f
        q q q q q 
        \revert ChordName #'stencil
        bes8:7
        \override ChordName #'stencil = ##f
        q
        \revert ChordName #'stencil
    }
} % chordsB

\markup "Stretched spacing due to repeated, unsuppressed chords"
\score {
  <<
    \new ChordNames \chordmode {
      \chordsA
    }
    \melody
  >>
  \layout {}
} % score

\markup "Stretched spacing due to repeated chords, even with \\set chordChanges = ##t"
\score {
  <<
    \new ChordNames \chordmode {
      \set chordChanges = ##t
      \chordsA
    } % ChordNames
    \melody
  >>
  \layout {}
} % score

\markup "Stretched spacing eliminated by de-activating stencil"
\score {
  <<
    \new ChordNames \chordmode {
      \chordsB
    } % ChordNames
    \melody
  >>
  \layout {}
} % score