Re: optimising typesetting 2 voices with same notes

[Gilles THIBAULT]

> my question is how to proceed to have a minimal effort 

You can use this snippet
http://lsr.dsi.unimi.it/LSR/Item?id=654

%%%%%%%%%%
\include "changePitch.ly"
patI = \context Voice {\voiceOne \repeat unfold 4 { s8 c }}
patII = \samePitch << {\voiceOne c8 s8 } \new Voice {\voiceTwo c4} >>


\new Staff  { 
   <<
     \changePitch \patI \relative { 
           < d' fis>
           < d e>
           < cis e>
     }
     \changePitch \patII \relative { 
           d fis b a 
           g e fis g
           a a, a' g
     }
   >>
}
%%%%%%%%%%