I tend to find that when I am working on a novel project it generally takes about 50 pages or 12,000 words before the real basis of the story itself is charted. Usually by about page 50, about three quarters of what I had originally mapped out as the course of the story has gone into the scrap heap. Or at least that stuff is stashed away for a possible future story. Under the Darkened Moon followed this rule which I did not even consider a rule when I started writing it as it was my first project. However over time the law seems to be holding true. I have at least 50 pages completed in several other novels and each of them have resulted in 75% of the planned course being discarded or seriously revised. Be it The Half-Orc Princess, Cry of the Golden Wyvern or Her Lovely Blood, the 12,000 word rule has been a nemesis to the finest laid plans for each of them. Even a project I just started today as a sort of test story, The Arrow, completely went off in another direction by the 1,500 word mark and is, honestly, better than what I had sketched for it.
I attribute this to the fact that I seem to work better when actually writing than postulating and sketching things out. I just cannot see how everything fits together until I start actually writing the actual text. Maybe some other writers can. But I cannot. So I am just accepting this and embracing.