I haven't figured out any rhyme or reason yet to the process times of Form 1's and 4's. I usually check a thread dedicated to process times for NFA paperwork at another large firearms web site to see what the latest trends are and compare the dates people are getting approved - to my submission date. That usually gives me a heads up, not counting errors and returned paperwork.
My first Form 1 (2008) took 88 days, my second (2009) 137 days. I'm gearing up for #3 shortly, and this one will be via a Trust for the fist time. My examiner has moved on from what I understand (Ted Cutter), so I don't know how this one will work out.