Too often I'm let down when a dramatic event in a novel is skipped over and then relayed to me as a memory or flashback. I don't mean backstory, where readers are informed of events that took place before the novel started. I'm referring to events that could be written in the novel's real time as an active scene but instead are summarized in a character's thoughts the next morning while he sips coffee.
Sometimes skipped action really stands out. An author may have been setting up a confrontation for fifty pages, so I'm eagerly anticipating it, staying awake an extra thirty minutes so I can reach that scene before going to sleep. Then the moment comes, but instead of living it with the character, I read about it after the fact through dialogue or memory. I feel cheated.
I'm also not likely to stay awake reading this novel in anticipation again. Those aren't the reader reactions most novelists want to inspire.
Why does this happen? I think mostly it's fear of writing a big scene. It's easier to summarize than to put a reader smack dab in the middle of the action. But readers want to be in the action. That's why this reader reads, anyway. So buck it up, author, and write "live" action when you can. Once you do, you'll see how much better the scene is, and you can puff up your chest and feel proud.
There are exceptions to every rule, so of course there are plenty of exceptions to my little tips. The purpose of a scene may be to establish the terror of a victim who's about to be murdered, for example. Readers want to feel the character's panic, but depending on your audience, most readers probably don't want to see the carnage. That's a good place to cut away from the action and let the investigators deal with summarizing what happened in the next scene. Obviously, if the novel is a mystery, the action creating the mystery must be recreated, not shown. That's the point. And there are many other reasons to cut away from action to summarize it later, and doing so can be a great tool, but make sure your reason isn't that you, the author, were lazy.