For a ways now I've come to regard reading books as similar to the mechanical process of compilation as is done by automatic computers. The overwhelming majority of what I read is technical in nature, and over the years I've mulled over what I'm usually left with afterwards. Reading typically leaves me with a feeling of the books in the back of my mind, but most often the result is a few ideas from dozens, hundreds, or thousands that noticeably persist; this is the compilation. For very few books do I fiercely recall, or care to even bother attempting with recalling, phrases, or ideas, verbatim.
It's obvious that most, or all, books are larger than necessary to convey their ideas, and I suppose much of this extra space used is meant for portraying the information in a way accessible to humans, although it's clear much of it generally doesn't. There are academic papers I've read which require leagues more time to understand than books ostensibly many times larger, and yet contain more ideas.
Fictional works or those closely related, I prefer biographies, are good for entertainment, and easy to recall offhand in segments, but their primary result in mine experience is to create a parallel I may later recognize myself reaching, or instill a heavy sense of dread, so they're no waste of time.
Reading is, so importantly, a means to know the dead, or dead ways. To live in the present is poor. That field of automatic computing is younger than one century old, yet my life has been so enriched, by reading books with perhaps no ``present'' worth, yet which reveal to me things few alive discuss.
It seems likely that, for most books, length and information density will be inversely related; this is also affected heavily by their styles. A book of interviews can be read much more quickly than a mathematics book, or anything else which demands more understanding. Of everything I've reviewed so far, it seems fair that I should write, with perhaps no exceptions, the shortest books are the best.
I've ofttimes felt inadequate, comparing my brief articles against those of others, until I realized my works generally don't collate from others, and how such collation tends to be the cause for these long lengths; writing a concise article, it's more likely to be read as well, and I've several times written solely to have article for a pleasant date, yet some of these have received the most praise.
There are several books which have to me compiled to a solitary thought or two, yet this seems fine.