If you start asking about code coverage in every code review you participate in, you’ll teach people to expect the question, and they’ll start thinking about code coverage so they have a good answer for you.
If you rarely respond to emails but always respond immediately to IMs or to somebody showing up at your desk with a question, you’ll teach people that they need to show up in your face to get information from you. They’ll start skipping the emails.
If you teach people what what you won’t tolerate by not tolerating it, they’ll anticipate that and adapt accordingly.
If you teach people what you will tolerate, by putting up with it, they’ll anticipate that.
This happens whether you pay attention to it or not.