If I outline in too much detail I have two problems:
a) My subconscious brain is much better at plotting than my conscious -- which runs to boring and predictable because it works logically. But my subconscious brain works slowly and therefore only feeds me plot in dollops.
b) I totally lose the urge to write the novel properly if the outline is a complete but condensed form of the story. Hence my planning tools of spreadsheet and circular diagram, plus scrappy notes on Post-It notes. However much I actually write down, my brain knows that what it's looking at cannot be called a story and could not be given to a reader to read. So the thing still has to be written out in full.
Basically I have a skeleton of the overall structure: hook, complication, key turning points and ending. This is done in the mind mapping software, along with character notes. Chapter by chapter notes are done on the spreadsheet to generate the circular diagram, but filled in as the book progresses. In other words I do rolling planning so each chapter is planned shortly before it's written, not planned up front. But it is planned, so I don't end up writing irrelevant stuff, though occasionally stuff has to be added if I realise that a section is lacking in detail. Like when I added the scene where the Earth Mages sing the stones into the matrix in Moving a Mountain.