The following is an excerpt from the USA Today of March 31.
Donald Trump's lawyer said Friday that the former president will surrender to New York authorities.
Trump's lawyer, Joe Tacopina, told NBC's "Today" show on Friday that Trump was initially "shocked" when notified of the grand jury's action late Thursday. But the 76-year-old Trump "put a notch on his belt" and vowed to challenge the criminal case, Tacopina said.
What does "put a notch on his belt" mean here? It doesn't seem to match a commonly-held meaning — what is the remarkable success?
A success or achievement that might help you in the future is a notch on your belt. UsingEnglish
A remarkable success or achievement, especially one in a successive string, list, or tally of other such ones. TFD
Is this a common expression?