As with most things in my life, I like a moderation. When going on a vacation, I have to have an end destination in mind. I like to have a few "day trips" planned for the week I'm gone, but I also like to leave plenty of time for the unexpected cool--and sometimes obnoxious--opportunities that always pop up. When starting a book, I like to have a fairly good feel for my characters--though by the end of the first draft I always end up knowing them FAR better than when we started out. And before I start writing, I like to have some major plot and turning points identified and I make sure those turning points have escalating tension, but I do not need to know the end. In fact, I never know the end, other than it will be a happy one.
I tend to write complicated characters and plots, but this isn't intentional, it's the journey--the exploration of the characters as they move through the plot and the research, that morphs my simplistic story into the realms of complexity, but such is life. I don't greet a day looking for stuff to complicate/ frustrate my life--or something to give me personal growth opportunities--read painful life events that make you stronger.
Being a control freak, I always start out my day with a peek at my calendar to see what I have planned but then $%# happens. The kids come at you with imperative demands, kids get sick, spouse throws a monkey wrench--or four--into your plans. The pipes freeze so you have no water. Your mother gets cancer. The dog finds a skunk to to harass. It happens. All. The. Time.
As Oprah would say, the one thing I know for sure, is that the most successful people (including writers) are those who are flexible. They can write wherever, whenever. They don't allow writers block. They roll with the punches--when agents can't sell them. When publishers close their lines. When a book bombs. When the economy sucks. When they sell movie rights and get a HUGE advance. They make lemonade out of lemons and don't get fat when the dough rolls in.
It doesn't matter if you're a plotter or pantzer as long as it works. And it doesn't hurt to try different ways. Who knows, you might end up a hybrid like me. It's not a bad thing to be a plantzer.