Well, you sort of do, but I don't actually think the N1 test (from my experience of a bunch of mock tests) really throws in very tricky questions that require you to know deeply subtle nuances. It will ask questions where some of the options are "wrong because it doesn't connect to a noun like that" or "wrong because you can't use this with a command" or whatever, but to me that's not a very subtle thing. If you know what the grammar form means and how to use it then I think that is mostly sufficient.
