While doing heavy make-up of book texts I often need to get in a line or to space out a line. Doing this without having countless paragraph overrides (with the danger that by clicking "clear override" or applying a script everything would be lost) the only possibility so far is to make numerous paragraph copies, e.g., "body", "body+5", "body+10", "body-5" etc.
A possible solution could be to have the paragraph style definition with some kind of "ranges", maybe "Tracking: 0 - +30" with a default value "0". And the actual value could be selected in a panel. Hopefully someone has a better idea how to implement this better.