Currently Mastery Paths only allows you to open assignments or pages.  But here is how I use them:

Student takes a quiz. 

Student passes quiz and gets a congratulations page

Student almost passes quiz and gets short practice

Student doesn't pass quiz and gets a long practice

 

Once students complete their practice I have to manually reopen the quiz, or have a completely different quiz that they take.  What I would like to do is to use mastery paths on the practice assignments and set it up so that when they pass the practice it automatically gives them more attempts on the original quiz, allowing for a somewhat circular path.