David says we need to separate the phases of GTD: collect, process, organyze and review. But is it really possible? For example, you got a note from your boss. How can you just put into inbox for later processing without looking into it? Maybe that's an urgent task you need to do today or now? Or you got a call from your friend who told you to meet with him in the evening. You have to process that input on the fly and you can't just make a note and put into your inbox for later processing that could happen only i.e. next morning.
Of course, it's great to separate phases but is it really possible?