I do not explicitly work on going any particular distance off a turn, but I have started doing a lot of a drill we did once in master's swim.
The drill was called "around the wall". What you do is swim a 25 plus your turn. After the turn, you do a single stroke and stop. You turn walk back to the wall and do another 25 plus turn.
I like to do this drill when practicing gearing up my speed. The reason is because I am working harder and so the farther that I can go after the turn, the longer I get to rest. In freestyle, backstroke, and butterfly (all of which dolphin after the turn), I now effortlessly clear the solid part of the lane line and usually the next two markers. My breaststroke is shorter only because of the limitation that you can only do a single dolphin and a single pull before stroking.
With effort (which I reserve for master's drill which I disapprove of), I can get a little over half way before I start wanting to breath.