I think that in emulating traditional word processing techniques a bit of
flexibility is lost, and I am always tweaking headings.

I use styles such as heading 1, heading 2, heading 3 etc, each with
characteristic  "space before" and "space after" settings.  When these are tuned
to look correct with a normal 'default' paragraph following it starts to go
wrong when headings follow headings.  In a well-structured document it is
possible to have

HEADING 1
  HEADING 2
    HEADING 3
      default text default text default text
    HEADING 3
      default text default text default text

At the top there is too much white space among headings 1,2,3 so the result is
not as intended.  Manual trimming is required.  This is a lot of work, and can
get lost if styles are modified.

I would like to suggest that there be two types of spacing for paragraph styles
- fixed and overlapping.  The fixed spacing would always be applied, but the
overlapping spacing would be applied only if the preceding or following style
had no overlapping spacing.  If both adjacent styles had overlapping spacing,
then  they should err.. overlap.

Another alterantive would be for each paragraph manually re-spaced to remember
the setting as a delta to the style ("style spacing -3 point" for example)
rather than a fixed setting.  This would allow proportionate response to a style
change.  But I prefer the 'overlapping' concept, as this would mean I would have
to do no manual adjustment when headings followed headings