Originally Posted by
SoggyDollar
It is very time specific
if you browse the wait times :
http://awt.cbp.gov/
a pattern emerges; certain days and times are best avoided

I lost confidence in that data back when we were flying regularly to IAD ... it used to say >50 booths open for our arrivals, when there were usually just a dozen. However, the latest info suggests they're being a bit more honest!