Its hard to say, and really depends on just HOW fast the person shoots and how bad the shots are vs a perfect run and a set time (the constant).
So if the constant is a down zero run at the average time for the shooter, you would have to do math specific to the course to see how much faster your time between shots would have to be to make up for a down 1 target or even a down 3.
In my experience, i dont shoot fast enough to make up for misses. When I start seeing down 1's my times start to drop. I try to go as quickly as possible obviously, but I personally put more of an emphasis on accuracy.
this is something Ive wondered about myself.