Donna Tartt's works are long. Very long, and that raises questions, the first one being: how does one keep a reader reading for that long?
It's a matter of raising stakes. The characters must make choices that are more and more important and that have greater and greater risks.
It's a matter of keeping things uncertain. A character should fail often enough so that the reader can't simply anticipate success. A character should win only enough to keep the reader from losing heart entirely.
It's a thrill to read through Tartt's scenes and appreciate and enjoy them enough to go back through.
This is not something I do well enough in my own writing, but I truly believe that by reading excellent authors who can do this, seeing what it looks like, and doing the same things in my own books, that I'll get better at it.
(Once, when taking a personal vacation through the Mississippi Delta, I stopped in Tartt's hometown of Greenwood, Mississippi and said a little prayer to her muse.)