When the NHRA mandated a reduction in testing to just four days over the course of the 2009 season, the Top Fuel and Funny Car teams quickly adjusted. Test dates became valuable, very valuable. Team's use to camping out the night after an event to test on Monday no longer had that luxury. So they adapted. If you couldn't test on Monday then test on Friday and or Saturday during the event.
At first, teams were quiet about their plans. Then, as more and more questions arose, drivers and crew chiefs started to hint at how they were using qualifying sessions to test. It wasn't perfect mind you, but it was better than nothing.
Tony Schumacher, driver of the ARMY-sponsored dragster in the Don Schumacher stable, was one of the first to publicly acknowledge his team was using as many as three of the four qualifying rounds to test. With the best conditions to qualify typically being the night session on Friday's the team could easily test during the first session of qualifying. Then, if the Friday night run during the second session was good enough, they could test in sessions three and four on Saturday.