I normally set up my beginner students to be 15 on the front foot and 0 on the back. If you are just a beginner , 90% of the time, you are going to be going one way. When you go to intermediate to advanced riding, you will be wanting to sink down and towards the tail of the board when you are finishing your turns. Its kind of un-natural and harder to sink down on the backfoot when your knee is pointing towards the tail of the board.
Just do a simple experiment, lay your board flat on the ground and stand on the board as if you have your both your bindings at 0 degrees. Now bend both knees the same evenly, Your butt should be in the middle of the board.
Now turn both your feet say 45 degrees forward (just to exagerate) and now bend both knees evenly, your butt should be moving towards the tail of the board. which is where you want your to be moving your weight during at at the end of your turn.
Also if you have a massive duck stance, draw a line along the binding angle toe edge to the heel edge. Compare the distance between the 2 feet on the toe side to the distance between the lines on the heel side.
When are you are flexing, naturally on the toeside you are pressuring the outsides of the board which is what you want to be generally doing when turning. On the heelside, if you have a big duck stance, you will be pressuring the middle of the board which is not what you want to be doing at the beginning or the end of your turns.
Hope this helps a little bit! I'm not against a duck stance as I ride a little duck myself, but if you are just into free riding and going in one direction, the forward stance will be working better for you especially on the heelside which if you ask any intermediate/advanced rider is the harder of the 2 turns.
There is a reason why racers have a forward stance