It is not necessary to memorize them, however you should have a good understanding of what is required for each of the processes. I found it helpful to make flash cards with the process on one side, and the ITTO’s on the other. When I was able to identify the process based on reading the list of ITTO’s, I felt like I had a good understanding of the processes. But I never tried to memorize the ITTO’s. Many people also find the process game in Rita’s book to be helpful, but personally, I found it confusing.