yeah, i find when i ask junie to write code to change things it often just piles on more crap instead of changing stuff. very often i wind up rewriting parts of the code and if it fails to actually debug shit and make tests pass, after 3 times i just usually end up writing the code that was needed by hand. and then, of course, the tests pass because it was written the right way.
they can sometimes save a lot of work but sometimes make more work. learning how to avoid those potholes they fall into is a key part of making the work more efficient.