Though I tend towards speculative fiction, I’m a big stickler for what I call “reality” – Characters should react realistically to situations. If confronted with a vampire will you instantly believe in them? No. If someone says “I’m a werewolf”, do you buy it? (Hint: the latter has happened to me. My first thought was “this guy is a lunatic.” I was probably right.) If something bad happens, your characters should react realistically, and take time to recover. However, just as different people deal with situations in their own way, so do your characters. While the death of a parent might throw one character into the dregs of depression, another one might bottle it up and move on as though nothing had happened. When my grandfather died one of my Uncles went to the bar and got drunk. The other went bowling with his friends. A reader might call the second one an unrealistic reaction, but it obviously wasn’t for him.
So, even if you know your character’s reactions, how much is too much? When do “the haunting nightmares” of someone who was attacked by supernatural creatures go from being “haunting” to being “Come on and get over it! Geeze”? When does “Oh, I just met you! I can’t be in love with you, yet!” turn into “For crying out loud, get ON with it!”? etc. etc.
There’s no golden rule. One reader/writer’s “Get on with it!” is someone else’s “But they just met!”, especially in books that cover very short spaces of time. A controversial example is the popular Twilight series. When I took the story out of itself and only looked at calendar days, Edward and Bella fall in mad, passionate love so fast that it’s mind boggling. But, when I first read the book it wasn’t horribly paced and didn’t stand out as being too much of a rush.
I think a lot it depends on the genre and “point” of your book. If the main story is the protagonist’s struggle to come to grips with abuse suffered at the hands of their alcoholic father, then 200 pages of emotional turmoil are a good thing. Conversely, if the point of the story is that the protagonist becomes a dragon slayer and saves the kingdom, you don’t really want page after page of wingeing.
Another consideration is how long your book is and how much (1/3, 1/4, 1/2 etc) you want to devote to the reactions of certain incidents. In reality, something like being attacked by killer monsters would probably leave hellacious emotional scars that would never heal, and might lead to psychological problems, but how much of that do your readers want to read? How much of that do you want to write? Will your characters continued reactions slow down the plot (ala Harry Potter’s seventh book and the realistic – but long and boring – camping scenes) or will they fuel it?
How much reality do you like in your books? How much is too much?