Very good advice. An implication from being reluctant to introducing dependencies is that you should remove dependencies if you can. Perhaps different parts of the system is using different PDF-generation libraries, or some clever person introduced Drools at some point but you might as well convert those rules to plain old Java.

Tooling is important too. IDE:s are great, but one should also use standalone static analysis, grepping tools like ripgrep and ast-grep, robust deterministic code generation, things like that.