Chess Tactics From Scratch -book

Finally finish this book after 6 months.
It was a tough read at times, but really enjoyed a few chapters.
Each of the chapters covers a theme and breaks down the ideas behind the tactical idea. Which definitely helps me understand how to spot them.
When you get to the puzzles you can reread each chapter to refresh the ideas if needed. I did this on about half of the chapters.
Some of the puzzles are very hard. Puzzles took me 4 months to slog through. Some took me 10 minutes a pc .
So progress can be slow. When i got to the puzzle section on candidate moves things seemed to somehow finally all come together. Feels like the effort is now worth it. Are my tactics stronger? Yes . I was already decent at tactics, but now when i play any kind if tactic I kind of look for themes I have learned in this book, and in an organized way like the candidate move chapter explains.
It was a tough book to get through, but I am glad I read it. I find most tactics books tough to read though.
Its not like puzzle rush. Its more like a difficult puzzle that one struggle with and at the end you hopefully learned something.
The author should flip the board when its black to play. Other than that I had zero issues with book. Im 1700 rapid on chess.com for what thats worth