In my opinion the condensed nature of the supplementary material is great if you have been exposed to some of the curriculum at some point. It is also a gigantic time saver. However, if you have very limited knowledge of the curriculum as a whole I would get both. Hopefully this helps.
Some people don’t use any other providers apart fr CFAI. I don’t think that works for me though.
What I used was to get the ‘basic package’ from schweser, notes and one practice exam book, and bought extra practice exams. Worked well for me so far.
@wtcollison I did the same as well. Used Schweser pretty much for all my levels, but I think CFAI has gotten better since then. I’d advise using the curriculum as a reference and for end-of-chapter questions, especially in L3.