"How important is tummy time? My daughter (7 weeks) screams whenever I put her on her tummy. How bad would it REALLY be if I just let her hang out in the bouncy seat during her quiet alert stage? I feel like I'm torturing her when I force her to stay on her stomach, and then the whole quiet alert stage is destroyed."
You know most of the time I say to do whatever gets you through it and makes everyone happy, but this time I have to say it: Tummy time is important.
Tummy time lets your baby's brain and neurons and muscles and nerves and reflexes develop progressively, they way they need to, to support more advanced activities like crawling and walking and running 5Ks and writing legal briefs and doing the Cha Cha Slide.
It's not the enforcement of tummy time that's important, it's the opportunity. So that means that you need to give her the chance to be on her stomach, but that it doesn't have to be painful, and that once she gets past that stage she's moved past it. So a baby who responds to tummy time by rolling onto her back doesn't need to be forced to stay one her tummy--she's developing appropriately by learning to roll over.
Remember the whole brouhaha about exersaucers? It's the same thing. The problem with saucers is that the kids don't get the chance to hang out on the ground and learn to crawl. It's the chance to spend enough time on the ground that's important, not advancing through a rigid series of steps to learning to crawl, as kids get there different ways. It's the time being allowed to work the movement through on their own. So as long as you're leaving your kid on the ground for enough time every day, saucers are fine to rotate through the repertoire of things to keep your kids engaged.
At any rate, the best summary of what happens developmentally during the tummy time months is written by Rachael Carnes of Spark Plug Dance in Eugene, OR, in this article "Great Stuff Happens Before Walking and Talking." And the best list I've seen of how to make tummy time fun and not torture is also written (not surprisingly) by Rachel in this article "It's Tummy Time!".
Thoughts about tummy time? One of the coolest things Rachael told me (back when we were in a mothers' group together when our 8-year-olds were babies) is that the way humans develop as babies is the reverse of what happens when we get old. So babies start out curled up and breathing, and develop greater movement abilities. And as we age toward death we lose those movement abilities gradually and end up curled up and breathing. A little morbid, but also extremely cool.