Having flown into Chicago and other busy US airports which are often subject to flow control, the class E from FL180 down to A080 never proved to be a problem even when we were under flow control.
Good thing you do not operate into Reno then eh!
Pictures and Video: Glider collides with Hawker 800XP on approach to Reno airport, forcing emergency gear-up landing-01/09/2006-London-Flightglobal.com
ASN Aircraft accident Raytheon Hawker 800XP N879QS Carson City, NV