I was reading the mathtools documentation on
\DeclarePairedDelimiter, and apparently only the starred version of the command it defines uses
\right on the delimiters.
This surprised me a little bit, because I've always used
\right on every single
\newcommand I define which uses delimiters, I just figured there's no reason not to. Which brings me to the question.
Is there a reason not to always use
\right on every pair of delimiter in your equations?