Believe it or not, engine wear and friction goes up when you first change the oil. So you don't want to change it too often.
Various studies show this, but this is the only one I find right now.
Valvetrain Friction and Wear Performance with Fresh and Used Low-Phosphorous Engine Oils - Tribology Transactions
Re 0w20 oil, why not give some room for degradation and use 0w30?