Soulcatcher is right on .. based on much reading and discussion here is how I envision it.
Think of a circular target when you aim your club out in the fairway or on the green ... much like a dartboard on the ground.
Each club has a precision rating ... the higher the rating .. the smaller the dartboard. So a club with 2 dots of precision will have a larger circle than one with 4 dots of precision.
On a perfect shot ... no wind ... perfect hit .... the ball will land somewhere randomly within the circle "the dartboard" on the ground. It won't hit the center .. it's random ... but it will hit somewhere within the dartboard. If that dartboard has a diameter of 10 yards (across). the ball could land 5 yards either side or 5 yards long / short of the center point. It's Random.
As SC said --- the lines are a forgiveness zone ... As long as you swing before those lines start to move ... the circle will remain a constant size.
Once those lines start moving in towards each other ... the circle will get larger ... thus the shot will not be within a 10 yard diameter circle .. but it will grow larger .... maybe to 12 or 15 yards or more. Even if you ding the shot and hit it perfect ... it's still Random where the ball will land within the size of the circle ... so it's to your benefit to hit when the circle is the smallest ... before the lines start moving.
I don't know the exact circumference of the circles, i'm not sure anyone does ... i made up these numbers as an example... but this is how I believe it works. Perhaps someone from WGT can confirm.
My recommendation is ... if your not sure of your shot ... figure out how much backswing you want ... make sure you know it .. then let the meter run through the first swing. On the 2nd one ... bring it back and release before those lines start to move.
Just my opinion ... Thanks,