Not sure where gbadman is, but a similiar situation I often see at the circle interchange in Chicago waiting in line (as you should do in that case) can easily cost you several minutes.
Two places that I can think of this being brutal are taking Decarie Blvd exit from Decarie North and taking the 20W exit off of the 13S. I'm sure that are some other pretty good examples out there.
1: http://www.tomtom.com/lib/doc/congestionindex/2012-1003-TomT...