Just learning the ITTO by heart will probably not help so much. It is more important to understand the logic and the process flow behind.
In the test there will be no questions like "You are in 'Collect Requirements' what are the outputs?". (at least I did not get any questions like that). The questions were more like "This situation went wrong, what did the Projekt Manager forget?" You will then have to first decide which step of the process you are in and then what has to come before. If you do not understand the logic, you will have trouble answering these questions.