Two of my kids are using it one grade behind. My oldest is 3 grades behind because level 5 is the highest level out (and she hadn’t done much grammar or writing). Somewhere I read students should finish levels 4 & 5 before high school. Honestly, the levels repeat quite a bit, so placement isn’t a huge issue.
It is a cross between CM and classical methods, so the grammar is covered earlier than other CM programs. The grammar in level 2 is pretty light though…DD just labels things like nouns, pronouns, and verbs, and memorizing definitions of the parts of speech. We haven’t used Level 3, but Levels 4 & 5 have lots of diagramming (with Level 4 having a bit more than Level 5). My understanding is that Level 3 focuses on narrations, and Level 1 teaches a bit of capitalization & punctuation.
We haven’t done much with the copywork. Two of my DC are using Print to Cursive Proverbs. My oldest selects her own (Levels 4 and 5 have them pick their own passages from the literature or another book they are reading).