I just discovered that you can do Mission 8 DIRECTLY after you did Mission 1. The reason is the button "Next Mission" after a mission (the screen where you see how many points you got in a mission). If you press this button 7 times before the screen goes black, the game will actually send you from mission 1 to mission 1+7=8!

Video following. I wonder if this will be an available/allowed glitch in any%. I personally would say yes because you would still complete the campaign with doing the 8th and last mission. But I'd be curious what you guys think about this skip! (Campaign run would be 30 minutes or something then?)