Here's how it works.
I do a loose outline. It keeps me from having scenes in the first 1/4 to 1/2 that don't move the plot forward. I say 1/4 to 1/2 because that's where I'm most likely to go astray. But I'm so much more ignorant of my outline for the latter portion of my book. Or forgiving - put whatever label to that you wish. I found that when I tried too hard for too long to stick to my outline that it put a damper on my creativity. I've only followed my outline to the T one time, and something about that story just lacks...soul? Intrigue?
It's just not my best story, but it's so much better than my first one which I didn't outline at all. That first novel has major issues that I don't know if I will ever fix. I've rewritten it so many times, but I don't know if it'll ever be publishable.
I'm a huge proponent of outlining. And I'm a huge proponent of being lenient with it. Lenient not for the sake of writing scenes that sound fun even if they don't progress the plot, but to let your character guide you. Sometimes what you have your character choosing in order to hit those plot points isn't what your character wants to do. That sounds crazy, but maybe your character is already on his/her path to a character arc. S/he wouldn't choose to vandalize a billboard because of peer pressure anymore. But there's something else s/he can to do keep that plot point rolling...fake the vandalism?
So, my advice is to write the outline so you'll know what is supposed to happen and you don't have a bunch of random scenes that sounded great at the time. Now you won't have to figure out which of your darlings you're going to have to kill. But be flexible for growing characters. Let your outline turn into a guideline.
