Barbara Trapido and non-plotting

Having listened to a number of authors talk about their writing over the past few weeks, I thought I'd heard every variation of "to plot or not" - until I listened to Barbara Trapido talk about her process. Her descriptions of how she writes a novel started with "a habit of talking to made-up people" and then writing down their conversations. No plot. No idea of a plot. Just lots of pieces of characters and conversations that gradually fall into patterns, and then into a story. She says they are puzzles that fit together rather than plotting.

For her, the characters are the plot. The story is there "under the water somewhere" and if the characters are well-realised enough, it will come together. She also said "your brain is grinding away and making this intricate spider's web in which everything connects". But she admitted that she finds chronology the biggest headache - where characters go and when, the plans of houses, moving people around. I think this involves a huge amount of trust in your subconscious, believing (or perhaps knowing after doing it for a long time) that it will all work out. She did originally throw out bags full of pages before things started to work with her first novels.

I also went along to a library event this week with crime writers, Michael Robotham and Malla Nunn. Often crime writers are the ones who will talk about plans and plots and clues and red herrings, but both of these writers said they have no idea what will happen next - they just keep writing. Michael said often he'll be about 10,000 words from the end of the novel before he starts to see what the ending might be. He also said he's written 30,000 words of something and had to throw it out.

The seminar I went to with RJ Ellory and Peter James was like an extended conversation rather than a class. Ellory keeps a notebook of what he has written so far - events, characters, etc - but he also doesn't plan ahead. Several authors mentioned Jeffrey Deaver who apparently writes 150 page outlines for his novels! I have to say that I need to know where I'm going in order to write. I might change my mind, because all kinds of things can happen as you write, including characters who take unexpected turns and detours or reveal new information. But I diagram what I think will happen, and keep it as a safety net.
What do you do?