The basic question is: Do you have enough to match the IBUs? Hallertau AA% covers a large range. If the recipe called for 1 oz. of NB @ 9% and 1 oz of Cascade @ 5% and your Hallertau is 5-6%, it will work. If it's 2%, then no.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
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