how to progess past 1200

You don't need 3 -4 hours of tactics each day. 20
Minutes a day must be enough.

You should study the other areas of the game as well

Here is a few games with commentary on typical mistakes players make in 1200-range and what to improve. Quite instructive.

https://www.youtube.com/watch?v=66E1S3urRM0

20 minutes a day is not sufficient to be 1800 in one year. It is not useful to study the other areas of the game below 1800. Before 2000, if you're better tactically, you will win the game, even in 30+0. Trust me. I made 800-1850 just by doing 3-4 hours tactics in about a year.

I thought this thread was about “how to progess past 1200”.

"... This book is the first volume in a series of manuals designed for players who are building the foundations of their chess knowledge. The reader will receive the necessary basic knowledge in six areas of the game - tactcs, positional play, strategy, the calculation of variations, the opening and the endgame. ... To make the book entertaining and varied, I have mixed up these different areas, ..." - GM Artur Yusupov

A jedi master here?

One can get some idea of the lasting scope of the respect for My System by looking at:
https://www.chess.com/article/view/the-best-chess-books-ever
Still, it might be noted that My System apparently did not occur to GM Yasser Seirawan as something to include in his list of personal favorites, and Aaron Nimzowitsch was not identified by the GM as a very worthy author.

https://www.chess.com/blog/RoaringPawn/an-open-letter-to-the-four-time-us-chess-champion-gm-yasser-seirawan

https://www.chess.com/blog/GMYAZ/open-letter-response-user-radovics-letter-to-me

My System has accumulated some direct negative commentary over the years.
"... I found [the books of Aaron Nimzowitsch to be] very difficult to read or understand. ... [Nimzowitsch: A Reappraisal by Raymond Keene explains his] thinking and influence on the modern game in a far more lucid and accessible way. ... The books that are most highly thought of are not necessarily the most useful. Go with those that you find to be readable; ..." - GM Nigel Davies (2010)
In 2016, IM pfren wrote:
"My System is an iconoclastic book. A lot of things in there is sheer provocation, and it does need an expereienced player to know what exactly must be taken at its face value.
I love 'My System', and I have read it cover to cover one dozen times, but suggesting it to a class player is an entirely different matter."
Also: "[Some things] ARE wrong, and it's not easy for a non-advanced player to discover those wrong claims.
Nigel Short has claimed that 'My System' should be banned. Stratos Grivas says that the book is very bad. I don't share their opinion, but I am pretty sure that there are more useful reads for class players out there."
Although he is a fan of My System, IM John Watson similarly acknowledged (2013) that:
"... Not everything in it has stood the test of time, ..."
http://theweekinchess.com/john-watson-reviews/john-watson-book-review-108-of-eplus-books-part-2-nimzowitsch-classics
One last point to keep in mind is that, even if My System would eventually help a player, it might not necessarily be helpful to a player now.
"... Just because a book contains lots of information that you don’t know, it doesn’t necessarily mean that it will be extremely helpful in making you better at this point in your chess development. ..." - Dan Heisman (2001)
https://web.archive.org/web/20140626180930/http://www.chesscafe.com/text/heisman06.pdf
A My System sample can be seen at:

https://www.qualitychess.co.uk/ebooks/MySystem-excerpt.pdf

A Chess Praxis sample can be seen at:

https://www.qualitychess.co.uk/ebooks/ChessPraxis-excerpt.pdf

Various samples:

https://www.newinchess.com/media/wysiwyg/product_pdf/9027.pdf

& T. J. Beach

Old english notation like 1. PK4 PQB4 2. NKB3 NQB3 3. PQ4      if I remember.

Thanks friend!

I'll also be looking for reviews, to update myself on people's perceptions.

Well, as of today, I have put out almost a dozen - well, maybe 9.

2 or 3 are really worth it.

I spent a month or so on my smaller books, 3 months in writing for "The Secret of Chess", 4 months for "Neverending Tactics", and 8 (!) months on "The Fine Art of Chess". Draw whatever conclusions you can yourself.

And yes, book publishing is a substantial portion of my livelihood, as of today.

I quit everything to do and analyse chess 24/7, which I have been doing consistently for the past 5 or 6 years at least.

Let the force be with you!

I think pattern tactics work a lot faster than doing 3 or 4 hours of random tactics every day.

At some point, a person will have to start doing combination problems

Combinations are similar to tactics but the goal isn't stated outside of a general concept, and solving a combination might net you a mate, a material advantage, or even just a positional advantage.

Pattern tactics is when you solve a bunch of problems with same pattern. Almost always in the firm of a mate-in-x.

For example, solving one hundred back rank mates, with all the problems coming from actual games.