My hypothesis for why people with later interview dates get earlier decisions is that they may want to compare earlier interviewees to later ones to ensure that having a later interview date does not disadvantage you. Sometimes people get quick interview to decision turnarounds because the admissions committee may really love a candidate and not feel the need to wait and compare them to the rest of the pool.
NYU's process looks very similar in terms of later interviewees often getting post-II decisions before those who interviewed earlier, and this is the logic/explanation the dean provided. That being said NYU does communicate 3 weeks post-interview (either R or continued review) and wrapped up all decisions by mid-January. I feel very fortunate to have a school I'm pretty set on and am not necessarily holding out on UMass, but it definitely is frustrating that they're not giving people finality when in reality at this point probably not everyone is being considered.
