A visitor to our home last year said to us, in a conversation about literature, that she had no patience with long works (for example, novels) – she appreciated what is short and to the point. (I paraphrase.) Do the people of today have the time, or patience, to spend much of their precious leisure time to read long novels?
There are alternatives. Firstly, there are television and film (movie) adaptations, which aim to convey the essence of the original and which require the actors to convey their feelings and thoughts through body language. TV adaptations in serial form allow the adaptor wider scope to deal with a long, complicated story.
Secondly, there are audiobook and radio adaptations, in which actors read either the whole of a book or else an abbreviated version (the latter, particularly, in radio). An example of the latter is the recent BBC Radio 4 series of Émile Zola’s ‘Rougon-Macquart’ cycle, set in the Second Empire of France. This saves me from reading many or all of the twenty! (I have read two better known ones – L’Assommoir and Germinal.)
I think that a case can be made that TV adaptations (in particular) of long “classic” novels are a valid re-interpretation of the originals. (See, for example, the work of Andrew Davies in Britain.)
I admit that those who have read the book are bound to compare and contrast it with the subsequent film or TV series and may consider the book superior. (I think, though, that the film of Jane Austen’s Sense and Sensibility, directed by Ang Lee  is better than the book.) On the other hand, viewers of a competent adaptation may be inspired to go back and read the original, with profit.
Of course, there is a large industry of films and TV series, written to a screenplay, without reference to a book. (Some screenplays are worth reading in their own right.)
Arguably, though, certain “classic” works – epics rather than novels – do not lend themselves easily to an adaptation that brings out their qualities, for example, those by Homer, Dante and Cervantes. This might also be said about Marcel Proust’s À la recherché du temps perdu and James Joyce’s Ulysses.
The key to the concept of adaptations for the screen is the focus on the literary genre of the novel.
What is a novel? It is a story about a stable group of characters, set in a particular time and place. The psychology of the characters is realistic – but some allowance may be made for caricature. The social background, indeed, the nature of the society in which the characters live is delineated realistically – perhaps with explicit or implicit criticism. The story has dramatic features, and there are twists and turns in the plot or plots. Often, the thoughts of some of the characters are open to the writer and hence to the reader.
The novel has been a predominant and popular literary genre for the past few hundred years, throughout the world.
Successful novels contain enough drama, dialogue and conflict to lend themselves to screen adaptation. Those set in the past are often called “costume dramas”.
Given the capacity permitted by the tv format, very long novels can be screened – even those like Tolstoy’s War and Peace (BBC, 2016) and Victor Hugo’s Les Misérables (BBC, 2019) – both adapted by Andrew Davies. In my opinion, they measure up very well to the needs of 21st century audiences-cum-potential readers. I am impressed by the tv Misérables. To me, both the story’s strengths and its weaknesses are revealed. I feel less obliged than ever to read the book. I am enjoying watching the tv series, to the extent that it makes me feel “less miserable”!