I do both. I blow out the lines from the closest to the furthest away. The pressure restricter used for water is 45psi and thats what I do. I also add pink rv antifreeze. It only takes just a little more than a gallon and its cheap insurance of protecting any low points that defy the blow out.
To me im not that thrifty to worry about a couple of bucks and guarantee that I wont have a problem. to each there own but as soon as you break a line and flood something you will wish you did. The air blow out never gets all the water out. there is always something left.