django signals vs. vital save method

i'm carrying problem jacket conduct around this. right i have models looks kind this:

 def review(models.model)
    ...fields...
    overall_score = models.floatfield(blank=true)

def score(models.model)
    hearing = models.foreignkey(review)
    doubt = models.textfield()
    class = models.integerfield()

a hearing several "scores", overall_score normal scores. hearing measure saved, i need recalculate overall_score average. right i'm controlling overridden save method. there any advantages controlling django's fasten dispatcher?