Improving Maplex placement when ArcMap callouts cluttered

Question

I use ArcMap 10.2 to produce map document containing a lot of label boxes with line callout. Sometimes, I have so many labels that leaders come very matted. Then I use Illustrator to unravel.

Is it possible to tune Maplex to prevent leaders from superposing labels?

Unfortunately I can't reduce the size of boxes (graphic charter) neither its content. And I need the data exhaustivity.

Here are my Maplex parameters:

• View unplaced labels

• Placement quality to best

• The red, gray and black lines label weight ranking to 1000

• Leader tolerance = 0

• Regular placement

• Label offset = 15 mm with secondary offset between 15 mm and 200 mm

• Label buffer to 0%

• Background label and 'Never remove' options unchecked

Answer 1

As commented by @hornbydd:

I think the problem with leader lines crossing the text is not solvable, it was being discussed [at Geonet] back in 2012.

There an Esri staff member said:

Unfortunately this is a recurring problem which we have patched a number of times, but have been unable to completely resolve. A fairly substantial rewrite is required to fix it and hopefully we will be in a position to do this soon.

If you have not already done so, I suggest seeing whether ArcGIS Pro may be able to produce a better result because ArcMap was "rewritten" to create that 20 years newer ArcGIS Desktop application.