pattern is full:
In terms of traffic flow, airports (ORD, MDW, JFK) with crossing runways are often only operating two or three at any one time, so the traffic flow and management problems may be just as "concentrated" as Heathrow's. Depends on a host of factors.
I flew into ORD and JFK a whole lot. MDW only a few times in the late 1960s when I was flying the DC-9-10. ORD has been improved a lot since I retired, but the JFK runway layout remains the same and it is interwoven to LGA because of proximity. JFK can operate only two runways at a time; 13L/R; 31L/R, 4L/R, or 22L/R. The exception, wind permitting when 22s or 4s are being used, they can squeeze in an occasional heavy international departure on 13R or 31L.