jsasker...when we say weaker I'm not refering to the strength of the tube itself. I'm refering to how much it will flex. The answer is yes, each arrow will flex more one way than another way. This test is to determine this. Example....fishing rods. Take a cheap fishing rod and whip it back and forth. You will notice that the tip will start out by going back and forth, but if you keep it up for a second or so, it will start to make a circle. The spine is fighting your whiping action. If you do that to an expensive rod, your whip will just stay back and forth. There is a machine they use to indicate the spine of the fishing rod and match the parts accordingly. The same thing happens with your arrow. You have pressure on your arrow from your nock, release and rest. As you release, your arrow flexes. If you don't make the weak side of the spine of your arrow the same (top or bottom for release shooters) you arrow will do the same thing as the cheap fishing rod, it will flex irradically until it is stabilized. Now granted it isn't going to make any difference to the hunter shooting 15-20 yards wanting a heart or lung shot (large kill area). But it does make a difference to the 3D or target shooter. The x's are a lot smaller. Just makes your groups smaller.