Some of us may be too young to remember the VHS tapes of old. Now with the DVD going the way of the dodo and Blu-ray marching in on high definition chariots, this long-time practice of rewinding a video is fizzling out faster than a copy of The Sixth Sense left out in a hot summer car. You could say that we're just a forward-moving society with no desire to go backwards.
Therein lies a problem.
With as quickly as we move forward in our daily lives, it's easy to miss things. You might miss the lost puppy whimpering as it looks for a companion, the old man sitting patiently for change to fall into his cup, or three commas you arbitrarily stuck in a sentence.
"What's that?" you ask.
"Commas," I tell you. "Three of them."
You say you read through the paper two or three times. I believe you, I do, but I think you're leaving out key details. How fast did you read through your paper? Sure, I could read through this blogpost in about thirty seconds flat. I could could read it three times in just as much time. Would I catch every error? I'll take a resounding NO for an answer.
You could take it slow, sure, but I still don't think you'll catch every error. Our brains work too fast to just slowly read something forward. If you're twenty-two years old and barrel-rolling down a hill, you'll find you can't just slow down--you're going to roll into whatever's waiting at the bottom of the hill like a lake or lake monster.
Think of your paper as a hill or, better yet, a mountain. You roll down the mountain, you're just going to fall and die. Metaphorically. So start from the bottom. Climbing the mountain, however, is a slightly different story. You'll go slowly, inching your way to the top, and, because you're going so slow, you'll be more careful to look for your footing. Such is the case if you read your draft from the bottom up. I don't mean backwards word by word--that would be like climbing the mountain with just your hands. But if you read it sentence by sentence you'll take it slowly; you'll be more aware of your surroundings and catch where you added the superfluous comma(s).
Going backwards sentence-by-sentence is an invaluable resource for sentence-level concerns as it forces your brain to slow the heck down and think more analytically. You're not influenced by the momentum of your piece and you can slowly move upwards to scour your piece for any flaws. The best thing about it is that, unlike mountain climbing, it's impossible to fall and die.