This Reddit post asks a pretty important question. I am going to paraphrase it here:
How can you use the Dice Chain to make sense of things like Strength checks, where an 18 Strength should have a real advantage over a 13 Strength?
This prompted me to write:
You could say that each additional attempt is made at -1d on the dice chain, which prompts players to let the strongest go first. (In fact, I will be using this from now on for checks like opening locks as well.)
And there you go. New house rule. Thank you, bored-n-curious, for making me think about this! I would never have come up with this solution without your prompting!