My Method for Reading long Books
I don't remember how I started writing the page number at the front of the book I'm reading.
This is probably frowned upon by bibliophiles, just like you shouldn't fold pages or smear a highlighter in a book.
In reality, however, it helps me a lot to write down the page number after every break in reading: two pages here, 15 pages there - and after a week you've read a 500-page novel. I also sometimes write a few words about particularly impressive passages.
In this way, I take a journey through a thick book, so to speak, with lots of small steps. At the end, I can see where I took a break.