It is fairly normal but it also depends on how accurate the broadhead's ferrule is and they vary.I found the STOS and new Grizzlies to have very accurate ferrules and took very little work to have them spin correctly,using steel adapters.
I used to spin mine,point down,on a board or table but in the last few years,I have used a spinning jig that I made and it is far ore accurate and shows exactly how much the point needs to move and in what direction.Putting my old arrows on the jig,told me they weren't as good as I thought.
A spinning jig can be fairly simple.It is just 2 "V" blocks spaced 8" or so apart.The arrow lays horizantally across the "V" blocks.There is a vertical surface in front of the arrow point and you establish a dot on that surface,using a point that you know is perfectly true.When you slowly turn your arrow,you can see instantly if it perfectly tracks on that dot or deviates from it.The jig makes it much more precise and much less trial and error than my old way and my broadheads have never flown better.