Another problem, depending on where you are at in the country, is dew on the track as it gets later. A few years ago I was an event that accidentally ran late. They had nitro and cut them to 1/8th mile run for the final and even at that they didn't really run all the way the the 1/8th. Between a wet drag and foggy windows it can get too dangerous if run too late. Not saying it couldn't be done, but there's more things to factor in.