So the current WIP is covered in red ink and blue Post-Its with the occasional yellow thrown in for variation.
The writing was easy, all it took was focus for ten hours a day and thirty days; yep, it's a Nano. The problem with Nano and that focus is that things changed within the story and you simply don't have time to return to fix it.
That's why so-called 'pantsters' (I prefer 'organic') writers spend so much time editing - to correct those... discrepancies. As the month wears on, characters change their eye colour, or motivations change or the conflict isn't strong enough. Even as strong as my concentration is when writing - to the point of putting milk in the cupboard and teabags in the 'fridge because I'm off planet in another world - it's still not good enough to avoid the pitfalls of changing thought.
With 'plotters' this isn't a problem because it's all there, laid out like a roast ready for carving (or a salad bar if you're a vegetarian). You cut the selected pieces and consume. Anything you don't like or doesn't fit, is set aside - maybe for stock later. Organic writers grab what's in the cupboard and toss it together; if done right, fabulous, if not then out come the herbs and spices with taste tests.
(Hmm... I missed lunch; maybe that's why the food analogy.)
Anyway. The result is nearly the same. I consider organic writing as 'fusion food', a mixture of this and that blended together for a complete meal. Plotted writing is the set menu, every course carefully balancing the whole meal. Each method provides satisfaction for the reader (or diner).
There's no right or wrong way no matter what anyone else says. It's up to each writer to chose their way. Do one or the other, or a mix of the two. Have a set entree, followed by a goulash and finished off with cake (mmm... ca-ake...). It matters not, only that you're comfortable with your choice.