I have to ask

I am planning to come in with a UK Ancesry visa, and have all the documents I need.
I was planning to just send it all in, wait the 5 working days (ok sweat the 5 working days), and presto! here it comes. But some of youse guys are applying in person, going for an interview. Is there an advantage to this as opposed to just doing the Fed Ex thing? 

Time.  Some people want/ need it done in a day.

I am afraid that mine might be rejected and I wanted to answer any questions right away then and there rather than wait more time to resubmit it. Plus, mine is a bit unique, student visa sponsered by my brit bf (I don't have all the $ for living expenses) and that will pose some questions from them. He's coming to NYC w/ me to make sure we get it that day just to be sure. Plus, we're both impatient.

I figured it was a time thing, I just wanted to be sure I hadn't missed a vital piece of information.
Thanks.