I have occasionally done the 'breaking the fourth wall' thing in my novels and stories. This comes naturally, of course, in a first person narrative — any story told in that fashion implicitly recognizes an audience. Perhaps being able to make remarks to the audience is one reason I like that point of view!
It is a little trickier when one goes third person, particularly if it is a limited third person voice. Any aside can be jarring and pull the reader away from the story. This has not prevented me from doing it a few times. If Thackeray could get away with it, why not me? I recognize that he was writing at a time when such devices were going out of fashion and greater 'realism' was the trend. But a book is a book; it is not real life.
So why pretend otherwise? The reader is fully aware that the author exists. I like to think of myself, at times, as a storyteller sitting in the marketplace, telling tales to a circle of listeners (I've written a couple stories that explicitly make the narrator such.). In this role, I would acknowledge and interact with my audience.
A little of this goes a long way, as the cliché would have it. It's not something to use over and over, but only dropped in very occasionally. And, admittedly, there are times when it simply does not work. The thing is, the aside should fit into the narrative, help illuminate it, rather than pulling the attention of the reader away from what is going on.
In other words, don't use it to comment about something else. Don't take the audience away from the story — you might not get them back. Ideally, such digressions will serve the plot, leading the reader right back into it.
Do not be afraid to reveal yourself. That is my point here. You, as the author, exist. You are part of your story and there is no reason to pretend otherwise, to follow some conceit of 'realism.' It's not real. It's a book. You made it up.
Stephen Brooke ©2016