Yes to consistency! I think there is nothing as frustrating as when you feel like the characters are being stupid for Plot, and not using a type of magic that was used before--unless why they can't has been explained--is just that kind of stupidity. Could be forgetfulness on the author's part, too, I suppose, but in that case, both s/he and their critiquers fell down on the job.

I think in my current WIP the use of magic is more of a spice, while the magic source is integral to the way the world works. The vast differences between these the use and its necessity for the world is what bothers me. That's why I need to work out if the use needs to be elevated to a main ingredient and how. However, like a spice, I can keep the uses small and show the characters what a dash too much do.