Re: automatic bar marks possible for ie, 28/4 ?

[Bertalan Fodor]

You can use something like the method written in the Line breaking 
section of the manual.
\new Staff { <<
\new Voice { \repeat unfold 10 { \time 6/4 s4*6  \time 4/4 s1 s1 } }
\new Voice { \relative { c4 d e f g a c b a g c d e f} }
>>

Bert