Every time I say people should wait 6-8+ weeks between sizes, I hear "you're not being realistic!" or something like that, so I would like to explain WHY I say that. First of all, since stretching is a permanant modification, I don't see how 6-8 weeks is that long at all. But besides that, here's why your ears need a break between sizes:
Think about what happens when you stretch your ears. You create micro-tears in the skin so the hole can expand to accomodate larger jewelry. The beauty of stretching earlobes is that they're naturally pretty stretchy, and unlike most other piercings they can be stretched without pain. However, to be stretched safely, the piercing must be strong. While proper stretching will not create any wounds, it does weaken tissue and a fresh stretch will be under more pressure than it was before. The tiny tears need time to heal back together AND build strength back up. With stretching it's not just about healing, it's about the ear being strong enough to stretch. So while your lobe may not be sore or getting crusty, it still needs time to recover. That just doesn't happen in two weeks for most people.
So don't think of stretching as expanding the hole, waiting for it to stop hurting, expanding it again, etc... think about it as expanding the hole, and then waiting for it to be strong and ready to stretch before you expand it again. Pain or resistance is an indication that your ear is not ready to stretch and going ahead with it could result in a tear, blowout, or a buildup of scar tissue.
I encourage you all to visit the forums on bodyjewelleryshop.com and read the threads about stretching. There are people on there who really know their stuff and they can explain it a lot better than I can. Also, check out these links:
Story about stretching gone bad from BME:
http://news.bmezine.com/2007/05/04/ear- ... -disaster/
What causes a tear:
http://wiki.bmezine.com/index.php/Earlobe_Tearing
Blowouts:
http://wiki.bmezine.com/index.php/Piercing_Blow-out