I haven't used levels 1-6, but from what I understand, about half the year is spent on grammar and half on writing.
I used levels 7-11. We did Easy Grammar Plus instead of writing one year to do one last pass at grammar, but for the most part we worked on grammar in the context of writing. EIW does include work on sentences, comma usage with clauses etc... which tends to be trickier for students (and the short unit on Prepositional Phrases in Level 8 made those really "click" for my dd as far as why we use them.)
EIL came out too late for us, so I never got to use that.