All depends what kind of finish and edge you are trying to achieve. More stones can be better if you are going for a true mirror edge or sharpening a razor. But as has been stated here, a 2 or 3 stone combo is great for what we do in the kitchen.
That being said, Glass Stones are pretty much my go to stones every day. I've gone through 2 of the 500's already (one broke because I dropped it on tile).
Stropping on the 16k glass really does wonders, I can echo those comments as well.
Personally, I stop at 3 points for my kitchen knives: 2k, 4k, and 8k, and that all depends on how the steel is responding. The only time I really go above this is when I'm honing razors, or just incredibly bored.