That is a fair point. Of course, that brings the number of Chromatic majiggers down to four, which abides by the law of 16.
Speaking of 16, why is it that there are 16 Shards? Is it because all the shards combined compliment each other?
Perhaps this is a viable theory: 16 is an Adnolasium related number, and therefore appears in the way a shard interacts with the world. 10 is a number related to the shardworlds themselves, and therefore appears in the way the world interacts with the shard.
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Okay, that didn't make any sense.
So, here's how that fits with what we know of numbers in the cosmere.
The reason that Allomantic metals are grouped into groups of 4, 8, and 16 is because those metals were present before they had Allomantic properties. Preservation "selected" metals in 16-based groups to work with allomancy. Not saying it was a conscious process, but whatever.
The reason there are ten essences on Roshar is that those essences existed on Roshar before, and that soulcasting does not actually add properties, just changes between those ten.
There are ten heightenings, I believe, because those properties existed already in humans, and are accessed by Breaths...
Okay, it doesn't work with that last one. I think this is more of a starting place, anyway.