Nothing that I wrote conflicts with anything you said.
Being in Tax Bracket C doesn't in any way imply you arent in Tax Bracket A.
The point is, Tax Brackets, and Taxes in general, are based on yearly income, so thats what people largely measure by once you are above a certain pay grade.
You get taxed by the year, so many people quote their income by the year, because its a quick and simple indicator of wealth/status.