Timing chain question

the extra keyways are there to fix slop in the manufacturing process of the camshaft
you may have a perfect example of a camshaft where it lines up dot to dot and is AS ADVERTISED

in that case, you can use the extra keyways to tune your engine, but you would not need them

now, you may also get a camshaft which is pushing the boundaries of the production process tolerances and then you need the extra keyways to get it dialed in as advertised