There aren't many "absolutes" we can reference in high performance audio. But, I think we can introduce one, with a high level of certainty.
Cable manufacturers design and evaluate THEIR cables using THEIR cables. There may be an instance where Nordost may use a Cardas interconnect with Audioquest digital with Mogami power cord as a final "quality check" to make sure nothing unexpected happens in the field. But, if we want to hear what they heard when those cables got the green light for production, we'd have to duplicate their cable set up to get there. Yes, I know, we don't have the same gear, or the same room, or the same source material, etc. but we can make the assumption (pretty accurately?) that their "weave" of cables was a single brand.
As one poster suggested, taking a one-brand approach may be "lazy". but IMHO it will get you to the finish line with predictable outcomes.
And, yes, as another poster added, internal wiring matters, and the chances are close to zero that it's the same cable you're using to connect your components. I wrote a post" "Thinking Inside the Box", which drilled down pretty deep into this.