Krutzer #2 is a great place for the teacher and student to really focus on both intonation, and bowing. In terms of intonation, the focus should be on sympathetic vibration (d's ring with the open d, a's with open a, etc)
This is also a good etude to really discuss auxilliary-note-shifts and confirm that the student really understands them.
There are many variations you can use for bowing. I agree that the best method is to start practicing the etude very slowly (listening for ring, no vibrato) until it is thoroughly learned, then go back and practice 2 notes to a bow, then 4, then 8. (graduallly increasing the tempo) You can also practice in rhythms. (use a dotted-eigth followed by 16th note pattern throughout, then switch to a sixteenth followed by dotted eighth).
I never let a student continue with other Kruetzer etudes until he or she has completely mastered #2 at multiple tempi, with 8 notes slurred, and completely reliable intonation. Sometimes that takes quite a while.
