If you are running late, you will miss your ADR. They won't hold it for you. But it's not like they are holding a table empty. I'm sure they figure on a certian number of no-shows each day. An exception would be one of the signature dining places - thus the cc needed. They won't charge your cc unless you are a no show.
On thetoher hand, if you have the dining plan, missing a dinner is bad, as it can be hard to replace a missed ADR, and you may miss out on the value of the TS credits.