Catching up with family and friends over the weekend is always very pleasant, especially if it involves eating out. It is even more enjoyable for a writer if some of those present are reading or have finished one's latest novel.
One person is reading 'Three Ages of Man', the second in my trilogy and said he could not find the third volume on Amazon. This of course is because I am still writing it. Another has now finished the same novel after at last finding her Kindle charger. It was lost during the process of moving; she thought that may have been why the middle part of the book seemed to move slowly.
Whether your readers have a real paper book or are dependent upon electricity,they bring their own experience to the novel, it is out of the author's hands. Sadly we can't expect every reader to take a week off work and live undisturbed in isolation, so they can give our novel the attention we think it deserves. Those who devour a book in a week and get 'lost' in it are the writer's dream. In reality people drop their paperbacks in the bath, can't read their kindle on the bus to work because it makes them feel sick, or lose their book down the back of the sofa. They read at bedtime and fall asleep after one page, or family dramas involving lots of form filling take over just as they reach chapter three of your novel.
Even if reading is proceeding well, each reader has memories and moods; they read your words through a prism of their own.
An author whose novel is turned into a film may see his book as others see it. We have all seen a film and thought it unlike the book. I saw a film after enjoying a well known novel and thought the film was rubbish, felt indignant on behalf of the author. I was later surprised to hear him talking on the radio about how pleased he was with the film adaptation.
Despite your readers' experiences and the impossibility of seeing into their minds, if they say they loved your novel and were left stunned by the ending you know they've read it 'properly'.