This is 100% dependent on person.
Alot of these crazy 37+ scorers on this site before they even started studying could have taken an AAMC practice test and gotten a 32+. For those who are starting from a much lower point, the time you spend studying is going to be alot more. The MCAT is a reasoning test and people who get 37+ type scores have great reasoning and thinking skills and hence don't need much practice refining or improving them. If you aren't this type of person and you aren't a natural reader/logical thinker, then you are probably going to have to spend alot more time prepping for this test and your ceiling in terms of the score you can achieve will probably be lower. There are some people who study months for this test, use their time well, and still have problems. Others literally spend a week lightly studying and get 37+ scores which is why I'm so hesitant to say "X amount of time is enough". You really have to experience this for yourself.
To go off this, some people have strong reasoning skills that they can figure things out with little background info on a subject. Others are more limited in this regard; they really need lots of content and background knowledge in a related subject to be able to guide them and help them in making conclusions on a similar subject even if they aren't being directly tested on facts. So how much content review you really need is up to you. For me, I'm not the most natural or fluid thinker; it really wasn't until I really really mastered the content and learned above what was expected of me(ie really learning everything in those Berekley Review books) that I really saw improvements in my score. That extra knowledge I didn't really need still helped me enormously in guiding me and improving my reading comprehension speed and in how fluid I was in understanding things and making conclusions from what I was reading. But this is incredibly variable by person.
My specific advice for you to be evaluate where you are now. Do practice problems etc. Maybe even take an old AAMC practice test, I think your verbal scores and even to a large extent Bio score and to some extent physics score can still give you a very rough idea of where you stand even for this new test. If you are getting 10+ scores on the bio and verbal section on the old AAMC tests, you really aren't that far off if you've already finished your content review. 3-4 hours a day for a couple months will be plenty in your shoes. If you struggle on the old AAMC Bio and Verbal you might need more time. This isn't a perfect guide but unfortuantely with how few AAMC released questions there are for this new test it's the best kind of guide I can think of off the top of my head.