What is a good exam technique when the exam is highly time pressured?

Make sure that you keep an eye on the time, and plan out how long you're going to spend on each question in advance of the exam. Always start by taking a moment to think about your answers, and annotate the question paper, rather than just writing everything you can think of down. Make every word count: you won't get marks for repeating yourself or for writing things which are irrelevant. Make sure you attempt every question: you get far more marks for starting everything than finishing one thing! If something went wrong and you get to the end and realise you haven't written something for a few questions, even writing some bullet points is a lot better than writing nothing.