No, it is not necessary to drill the advanced phonograms, as they are not a requirement for basic reading proficiency. The advanced phonograms are used only in a very small percentage of our words or only in advanced and technical vocabulary.
However, it can be helpful for students to become familiar with many of the advanced phonograms once they have mastered the seventy-five basic phonograms, especially older students. Familiarity with advanced phonograms can aid students in reading and writing words that use advanced phonograms and, in some cases, assist with comprehension by providing clues to the language of origin of a word.
For students who have already mastered the concept of phonograms and how they work, and who already know all the basic phonograms, the concept of advanced phonograms is not difficult. We have found that when these students come across an unfamiliar advanced phonogram in reading or spelling, they often recognize that the phonogram is making a sound they have not learned before and that it may be an advanced phonogram coming from a different language. They do not struggle with the concept because of their understanding of how English works.