Adjusting length of final line

[Dave Shield]

I've been trying to adjust the width of the final line of a piece,
where lines are being explicitly broken at specific points, and the
last line would naturally be significantly shorter than the others.
   If I use a non-ragged layout, the final line ends up overstretched
and looks ridiculous - if I turn on "ragged-last" then the final line
is compressed much more than the others.   How can I get the general
spacing of the last line to be similar to the other lines in the
following example?  (i.e. roughly half the width of the page).

I can't help feeling I'm missing something obvious, but nothing I've
tried so far seems to work.   Where am I going wrong?

Thanks
Dave

========= example =============
\version "2.22.1"

scale     = \relative c' { c d e f g a b c }
halfscale = \relative c' { c d e f         }

\score {
    \new Staff {
        \scale          \break
        \scale          \break
        \halfscale
    }

    \layout {
        %  If set '##f', the last line is stretched across the full page,
        %     and looks much too sparse
        %  If set '##t', the last line is compressed into a minimal width,
        %     and looks much too compact
        %  How can this line be scaled to occupy about half the page width
        %     and hence have the same spacing as the rest of the piece?
        ragged-last         = ##t
    }
}