OK, I follow your reasoning and it's likely correct. However, as I mentioned, the inner double chainrings I have do not have any rotational indicator (i.e. the little triangle) on them so it's a guess how they to be installed. Maybe the bolt hole with the tooth count and Shimano name engraved around it goes 180° from the crank arm the way it is on the one triple I have.

BTW, Shimano's installation sheet for the new 105 cranks (FC-5700 and 5703) does show a triangle mark on the inner ring of the double so the older chainring ones I have may be outliers.

Now, a question. What about a 40T or 45T chainrings where the tooth count is evenly divisible by 5? Are they exempt from rotational position effects?