Hello Kieren,
>>> Use
>>> \override TextSpanner.minimum-length = 30
>>> \override TextSpanner.springs-and-rods = #ly:spanner::set-spacing-rods
>> Thanks. Alas, doesn't work correctly for broken spanners
>
> Yeah, I saw that coming… as well as the fundamental
> "trial-and-error" problem.
:-)
>> I also wonder whether there is a solution (or should be a solution)
>> that doesn't need manual entering of a minimum length value that
>> can only be found by trial and error.
>
> Does David N's text-spanner work solve this problem, I wonder?
What are you referring to?
Werner