I interpret this as a "5" minute per screen goal from the time the press is empty from the previous job, to when you first touch the next order.
So when you first touch the next order, if you have a two color job, the first approved shirts should be coming down the belt in 10 minutes. Running the job, not just a strike off.
I always see this as a goal, because when you do your time study like I've done you may see that you are nowhere near this on some jobs, and some you are under, so it becomes an average for the day / month / year. I also found that we had a wide variance depending on the lead printer on the press.
This is always a goal, I think it's a like drink 5 gallons of water a day type thing, where you'll never achieve it in practice, some people online will tell you that they setup jobs in 2 minutes per screen, never touch a micro, but when they look in the mirror they know they are living a lie.