There are times when you can have too much detail in a story. A perfect example that I saw awhile back (I forget where) is describing your character's morning routine.
Just off the top of my head:
Stan woke at 6 a.m. He rolled out of bed, scratching an itch in his side, and walked to the bathroom. He put the toothpaste on the toothbrush and scrubbed his teeth like they'd been caked in dirt. He undressed and turned the shower on. Stan waited for the water to heat before stepping in. He squirted some body wash into one hand and scrubbed at his torso. Then he moved to his legs; then to his arms.
See how monotonous that is? And there are some writers who can go on for a page or more like that; describing every little detail of every scene, every action, and every setting. It wastes a lot of words composing something like that when the only desire is to show the character is A Normal Person.
Much better to use summarizing sentence(s) to show the same details. Let's look at my rewritten "Stan" paragraph again.
Stan woke at 6 a.m. He went to the bathroom first, where he brushed his teeth like they'd been caked in dirt. Stan turned the shower on and undressed while he waited for the water to heat. He washed under the soothing warmth of the strong spray.
Neither paragraph is tremendously great writing, but the premise still holds. The same information is communicated in a much shorter space than it was before, though the paragraph would probably be cut if I were writing a story about "Stan" for real. It doesn't really drive the story forward, and I'd rather not (as a reader or as a writer) see monotonous stuff included simply to pad the word count.
Summary is particularly effective in scenes where there's a lot going on. If you can touch on everything the character sees in one or two sentences each, then you can still communicate the details without getting into unnecessary description about how the battle fared or some such.
On the other hand though, there are times where too much summarization can kill suspension of disbelief. This is especially true when trying to succinctly describe an emotional response. Not everything can be summed up in one or two sentences, and the details need to flow where they create an engaging experience for the reader and not exist because the writer loves their own flowery prose (which I've also seen).
And before I forget, the Ten-Word Novel Contest ends at 11:59 p.m. U.S. Eastern Time tonight (December 31). This is also the last blog post for this week, so Happy New Year to all my returning and new blog readers!
See you in 2010!