Yes – if you are really sure that you understand them (and you have watched the lectures). It would be wrong to claim that they cover 100% of every exam, but for every exam they cover enough to cover at least 85/90% of the marks.
BUT what is so important also is practicing past (real) exam questions to get used to the style of the examiner. It has been the same examiner for a long time which is good. There is always the danger of misunderstanding what he is asking – however well you know the subject – but the more of his questions you have practiced then the less of a problem that becomes.