Gonna take 3 hours or more...
LOL. Way more. I did a planned speed run and it took me upwards of eight gameplay hours and about 12 real hours. I skipped all cutscenes, found exploits against the AI, and used a second controller to boost the character specific ones. Command Training alone has the potential to take three hours, especially if you have trouble with Akira's 1-frame knee (which you have to do) and the VF characters' on hit moves in general. Pai is easy but Sarah has some tricky stuff and Akira has the potential show-stopper with the 1-frame knee. The DoA cast is relatively easy for the most part.