Have any of you had a student that stays on one scale for over a month, or been on a scale for a number of months?

I have a student that began scales (major and related minor) about a year ago (would need to double check for sure >_~ ) and is only as far as G minor. The main problem is getting fingering down, and I'm *strict* enough so that I won't settle for an O.K. fingering; it needs to run smoothly instead of questioningly (if you get my meaning).
Each week we spend time on making sure the fingering is understood, and I point out helpful hints to help the student remember it that much more. I make sure they know what to do for their week of practice (and have them go over it during lesson, etc.) and they do it fine - during the lesson. But... argh!!! it doesn't seem to click at all in their minds and I'm really at the end of my rope on this matter.
I've gone over my own experience with scales to see if I could pass on anything new, but I've used all the suggestions my teacher used with me and need some different advice. The indivual student that I mentioned above is about 3rd year in lessons, if that is going to aid in an answer.
Anything else I intended to say... has slipped my mind at the moment. Any advice is greatly appreciated. Thanks.