Along with the draw weight of the bow, the arrow length and tip weight all factor into whether an arrow is spined correctly. Lighter heads and shorter arrows tend to make an arrow "stiffer"; whereas longer arrows and heavier heads make an arrow "softer".

For instance, I got some CE Terminators on sale this summer. They are 60/75's and I shoot a 61 lb. draw weight. But because the arrows are 31" long (I didn't cut them) and I'm using 125 gr. broadheads, they spine out just fine. I also can use the 500 series Easton Axis - if I cut them to 27.5" (arrow rest is at the back of the riser)and use 75 grain heads. But my mainstream arrow is the 400 series Axis.