We are really good at putting limits on ourselves. It’s human nature to think that the way we’ve always done something is the way it should be done. The brain loves a pattern, and it establishes them very quickly. Anyone who's ever tried to break a habit, or modify an existing one should be well aware of just how ingrained, how fast, things become.
There are all sorts of habits. Some have to do with how we live our lives, others have to do with how we think about things. Some are bad for us, most are good (or at least neutral). Teachers are not removed from this. We all have patterns of expectations, procedures, attitudes, ways to filter and deliver content, and all of the other aspects of the job. These are our preferences, and we prefer them mostly because they are how we, personally, do the things we do. They are the habits of our job.