Mike,

As others have indicated, the issue is trying to cram a ton of track time into a limited schedule. Double events have time for a qualifying session and a race each day. That's it. Keep in mind that at Blackhawk, we are restricted to certain hour as far as running race engines (8:00am to 6:00pm). With the worker break, that gives you about 4 hours in the morning and 5 hours in the afternoon.

Two-day single events like restricted regionals would typically have a practice & qualifying session on saturday and the race on Sunday.

BTW - The season ending regional event at Blackhawk in late october is traditional a two day single event with lots of track time and the races are longer too. It usually has one of the lowest entry fees as well. It's a fun event to finish out the season.