Per discussion with Dong and Ish...
Is consistency a good thing or a bad thing? It depends.
Some firms have the "consistency" through all their projects. Every project is the same: same way of thinking, same type of form... How lame is that!? But sadly, there are still people who believe in this type of "consistency." They call it "identity," or, more recently, "brand."
Other firms believe in variety - every project is unique. But within each project they are consistent from the central concept to it manifestation - form follows idea. This is interesting, but perhaps confusing at the end... Looking at the big picture and comparing the projects, people may ask: What are you thinking? Why are you jumping around? Do you really know what you wanna do?
Hmm... seems some sort of threat through the projects is important... I think the best consistency is to have a clear trajectory of thinking. You have a certain range of interests, but at the same time you honor the diversity of approaches, trying to explore different possibilities of manifestation. As a result, you will have a systematic variety of projects under certain theme(s). And btw, being consistent in this case doesn't mean the ideas are not evolving.
This last one, perhaps should not be called "consistency." Good that it has different ways of thinking, but the end form is always the same. People who are doing this may have a critical and analytical eye, but they only know one way to express themselves. I'll call that a limitation of imagination.