Originally Posted by Happy
If your score is in the low 700/690 range, you should heed drbond's advice and proceed very cautiously about "churning" cards. There is a huge difference between someone has a high 700 score and someone has a low 700 score.
You would be better off in the long run, to try to figure out WHY you have such a low score (being young is not necessary the correct reason), before you try so hard and poke around to "perfect the art of churning". There is no hard and fast rules because as drbond already so kindly hinted, there are so many variables involved in the processing of each application, no one can tell you exactly what would work and what wouldn't.
But I thought that there are SOME hard and fast rules. e.g. Amex only allows one bonus per lifetime, you can apply with bank of america every 30 days etc. I understand what you are getting at, but I certinly think you are overstating the case. We should be trying to open up this black box instead of seeing it as some mystical bundle of forces.