Lyrics too cozy with notes

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In the following example :

\version "2.17.9"

<<
\relative c' { g a' a r4 a1 }
\addlyrics { u u u u }
\relative c''' { r2 r32 d8.. r4 R1 }
>> 

I'm not convinced that the lower voice should slice through the lyrics.  I'm 
typesetting a choral works and it looks, while sightreading, that the u in the 
higher voice is a sort of annotation for the lower voice (the spacing is even 
tighter in my real example).

What does real literature do?  Does this type of typesetting ever happen?  I 
think it'd be worth it to horizontally pad skylines in Lyric contexts so that 
this sort of snug fitting doesn't happen.

Cheers,
MS