It’s as well to keep in mind what you should not be doing. Do not introduce lots of fresh evidence at this stage, though you can certainly introduce the odd extra fact that clinches your case. Nor should you go on to the ‘next’ issue. If your question is about Hitler coming to power, you should not end by giving a summary of what he did once in power. Such an irrelevant ending will fail to win marks. Remember the point about answering ‘nothing but the question’? On the other hand, it may be that some of the things Hitler did after coming to power shed valuable light on why he came to power in the first place. If you can argue this convincingly, all well and good; but don’t expect the examiner to puzzle out relevance. Examiners are not expected to think; you must make your material explicitly relevant.