Depends on the system and the specific play the other team is running. It also depends on the handedness of the ball handler.
If the ball handler can't go left, coaches will often instruct the defender to force the dribbler to go to their weak hand regardless of what spot on the floor it is.
My high school coach wanted us to give baseline. He felt the baseline was an extra defender. It was the help side defender's job to come across the lane and create a "3" man trap on the ball while the other 3 played a shell game against the remaining 4 opponents and tried to grab a steal from the trapped passer.
While his hand is being forced due to Billups, Turiaf, and Walker injuries I do like to see MdA using a bunch of different guys out there. Shawne has obviously been fantastic for us this year, Shelden some necessary big man depth, Carter is what he is but has at least been giving the effort, and I've always been a Mason fan and like the way he's been a professional about the way this season has gone. I'd like to see us go a little deeper on the bench when guys get healthy so hopefully we can continue to play well and force that to happen.