Thanks for the post. A few thoughts here:
Do the OD course homework drills overlapp with the T&A drills? Would it be better to focus on one or the other?
Yes, some of the materials with the On Demand Course do overlap with the Testing and Analytics package.
The On Demand Course material is formatted to coincide with the course syllabus. For example, Lesson 3 covers Weaken questions, so the Weaken drills are located in Lesson 3.
The Testing and Analytics Package drills do not follow a set syllabus, so you would work through those as needed. For example, the Weaken drill sets would be used when you personally want to practice Weaken questions.
So, what to focus on depends on where you are in your studies. If you are still progressing through the On Demand syllabus, I would recommend sticking to the homework and drill sets in the On Demand Course, since we have already curated that material for you. But if you have completed the majority of the course and/or a specific lesson, then move on to the Testing and Analytics Material.
Please note that encountering any questions a second time will not be detrimental to your studies.
I'm thinking that I should forgo OD drills and focus on T&A drills, especially since T&A gives comprehensive scores and tracks progress over time.
The On Demand Course material also gives comprehensive scores and tracks progress.