At http://www.k6if.com/wpx03/time_index.html there are audio clips of last year's WPX SSB. There are several periods of fairly high rate. Listen for example to the file labeled 12:10, 9th down from the top. About 5 minutes into that file the rate picks up nicely.
GL es 73,
***dan, K6IF
Try the California QSO Party, this Weekend!