Controlling hairpin length - revisited!

[David Sumbler]

After a 9 month gap, I have finally come back to Lilypond and will
attempt to finish tweaking my string quartet score and parts.  I have
installed v2.19.48, and I have run 'convert-ly' on my files.

The reasons for the long gap were (a) moving house in February and,
more importantly (b) feeling very discouraged by the apparent
unpredictability of hairpin lengths in Lilypond, despite all Harm's
valiant efforts.

So, for now, I accept that I am going to have to tweak errant hairpins
individually, using trial and error for the most part.

The only parameter that I am aware of that will affect the printed
length and position of a hairpin is Hairpin.minimum-length.

Just so that I have as many weapons as possible at my disposal, are
there any other parameters which might directly affect the horizontal
position of the left-hand end and/or the right-hand end or a hairpin,
or its length?

David