So rather than switching from side to side , you are pivoting around the center. As a consequence then you switch from working backward to working forward, or the other way round but in any case, always changing direction from side to side which effectively means you make an exact copy on both sides where I am always working in a consistent direction whether I choose to go forward or backward but creating something like mirror images on the two sides. Not that it has consequence for shedding the water because the escarpment of the cuts are facing up in either case so long as you hew with the bottom of the log facing up the water will always shed when placed in the wall. I wonder why go to great effort to keep the axe pattern consistent when this is not going to ever be apparent because the two sides will never be seen at once. Only the direction of the escarpment is consequential and that is a question of having the bottom always facing up when you hew. Is this because you always want to hew but end to top? In theory it makes sense because you are not cutting into the overlapping growth rings instead cutting out of the ends where each consecutive ring stops. The other way to work like that is simply change the angle of the cut to what fibers at that particular spot are telling you, in other words being aware of and reading the wood as opposed to adhering to the principle, but I'm sure you do that already. Do you try keeping the cuts more perpendicular or angled? When you rely on a pairing action it's, understandable, the amount of time it is taking.