I don't think you can get away with planning everything in advance to the very end, and then just write what you planned at the start. Even if you had outlined the whole novel, you'd probably be better off revising the plan when you reach the halfway stage, anyway.

By analogy, you can make a business plan for 5 years, but the forecast it's based on will carry a margin of error of + or - 50% in Year 5. When you get to Year 4, the plan for Year 5 will stand some adjustment. Now that Year 5 has become Year 2, the new forecast will be more accurate, see?

Morevoer, they say plot should flow from characters, not vice-versa; otherwise there's a danger of the characters feeling like 'plot puppets' - too transparent that an author is pulling their strings. X must fall in love with Y and murder Z in chapter 27 because it says so in the outline!

The problem is, you've got 26 chapters to discover your characters and for them to discover themselves and each other. By the end of that time, X might not even be terribly attracted to Y anymore, and forget why he's supposed to dislike Z.

If you're a builder, you need to finalise the architecture at the start and then be a control freak. I wouldn't like to live in the top-floor apartment of a block that was built organically. But a novelist? Once you have created characters, do you have any choice but to follow them? And how can you possibly know where they're going to take you?

I'm sure it's better to have an outline than not, but I doubt if having one gets you out of the need to revise and re-adjust it as you go.