I have a 800+ credit score : )
I pay on time and I have 5 cards of which 3 I do not owe any money on.
The way they score does not make sense as they give you points on using the same credit cards with the rising interest rates vs taking points away for swapping them out for 0% ones.
Swapping out for a new card lowers your score due to the credit inquiry. Do that a few times in a cople of years and that can lower your score by 30 points. Inquires stays there for 2 years. Plus the new card doesnt have the same credit history on it as the old. And if the new card has a lower credit line than the one closed, your overall credit available to used percentage gets worse.