What if the tutor plans to get into MCAT passages after I have the grammar down solid? Am I still getting sold unnecessary instruction?
Firstly, you might ask your tutor to give you their rationale for taking you through a grammar curriculum in preparation for a verbal reasoning exam. It may be that grammatical understanding can provide a useful tool for orientation if you are unaccustomed to complex sentences, but my own sense is that the actual process of communicating in language doesn't work that way. As an MCAT teacher my own approach has always been to encourage people to make the reading experience more direct and personal, less analytic, because reading is a kind of magic.
A book is made from a tree. It is an assemblage of flat, flexible parts (still called "leaves") imprinted with dark pigmented squiggles. One glance at it and you hear the voice of another person, perhaps someone dead for thousands of years. Across the millennia, the author is speaking, clearly and silently, inside your head, directly to you. Writing is perhaps the greatest of human inventions, binding together people, citizens of distant epochs, who never knew one another. Books break the shackles of time ― proof that humans can work magic. Writing is a kind of magic. - Carl Sagan
Grammar consists of the rules that speakers of a language apply subconsciously to govern the relationships of the sound patterns making up expression. For a fluent speaker, grammar works beneath the surface. It's not the content of an expression. Grammar isn't the author's intention. In the phenomenology of language the content is its referential, expressive and appellative dimensions, the sense of referring to external reality, expressing an internal state or point of view, or of posing a command or urging an action. This is what verbal reasoning is about. How deeply can you interact with the writing? Can you break through to understand the different levels of meaning, but grammar isn't an object of author's intention, except in some kinds of poetry and experimental fiction. Grammar refers to the rules underlying the language itself, which are a given. While there may be a discipline that involves working to improve grammatical understanding to exercise the cognitive skills underlying verbal reasoning in general, I am not aware of it. My own feeling is that to focus on grammatical rules is only going to add a layer of distracting content to an already stressful process.
In my opinion, you need to find a process, with a tutor or without, that enables you to practice and reflect on performance in such a way that leads to improvement. Try analyzing the questions you miss and asking yourself why, and try to improve your direct connection to the author in your reading. Imagine the passages you read were written
for you. It's hard to see how studying grammar is relevant, but nobody here is privy to your tutor's strategy. For my part, I have never heard of such an approach.