Louis McBride just raised the issue about using rabbinic literature in NT studies, noting that he’s skeptical of the approach. He quotes Amy Jill-Levine who notes a number of problems:
Rabbinic literature is later than the NT
It’s often prescriptive rather than descriptive
It’s often contradictory
I agree with all of those points. I’d say that I think it’s value is limited because it represents a divergent strain of Judaism. The NT and rabbinic literature grew in the same soil but are the results of different strains of the same seeds and manifestly different manners of cultivation. If anything, I think the rabbinic corpus can help us, at times, to understand Jesus’ opponents. I don’t think they shed a great deal of light on the NT in general though.