Hello! I assume you read this:
https://www.channelfireball.com/article
e9f08da14/
My main problem with this is that it falls apart when you try to recast your commander... for two more mana. You aren't going to avoid multiple slots in the curve.
With that in mind, I definitely try to lessen the density in my high-cost commanders' curve slots. For example, my Be'lakor deck with its 6-mana commander tries to avoid running more 6-mana demons. I try to focus the supporting cast on the cheap side to maximize his initial EtB or in the 7+ to maximize his subsequent EtB.
But I'm building a Lavinia, Azorius Renegade deck and will not be cutting Arcane Denial because it has the same CMC.