Outlining Plots and Characters in Mystery Novels

The last few days, there's been a lively discussion on the DorothyL Digest (http://www.dorothyl.com) about whether authors should outline a novel before writing Word One, or fly by the seat of their authorial pants. The responses confirmed a long-held opinion: no two writers approach their stories in precisely the same manner. Here's what I wrote:

For my first couple of mysteries, I tried to outline the plots and describe the characters in advance. But then, practically as soon as I started to write the story, the characters ignored all my a priori efforts. If anything, what I'd put down beforehand held me back.  So for the next four books, I became a pantster, started with a character or two, and a general idea of where they were going. Still rough sledding - first drafts took forever, and rewrites were extensive.
For my current book, I decided to try a middle approach. I took my initial characters and my general sense of direction, and wrote just a few lines about what they were going to do first, and next, and after that. Finally, after about five or six scenes, I hit a wall, and that's when I started writing the first draft. The characters fleshed out the skeleton very nicely, and as I approached the roadblock, I found I could look ahead from there. So again, I wrote short descriptions of scenes as far as I could see. I'd call it a Carrot and Donkey Approach. Four sequences, and I finished the first draft in about one-third my usual time, and then rewrites went at least twice as fast as usual, with many less drafts. The pudding that's THE RAGTIME FOOL should be in for the editor's proof in about a month.  
I guess we just keep learning. That's one of the great things about writing. You never know it all - at least I don't.
One more thing: to keep track of events and people as they develop, when I finish each chapter, I write a short summary of what happened, so as I go along in the first draft and with rewrites, I have a linear record of who did what to whom, and when. I'd be lost without that.

If there's one constant, it's this: published authors write regularly and frequently. But there don't seem to be any hard-and-fast rules on just how best to go about it. It's trial and error, with more than the occasional tribulation.