I started a long email explaining why I'd chosen that configuration. There needed to be a run up to conversation A, and you couldn't have A and B right next to each other, so X A X B was the absolutely perfect order. As I wrote my justification, I thought as a concession I'd try XAB, but that obviously didn't work. I tried A B - no, it definitely needed the X in-between. AXB was on the surface the straightforward choice, but that would mean rewriting the intro, rewriting the X interchange, writing a completely new run up to the A conversation. As I wrote explaining why my first choice had been the right one, I could feel this new scene in action, how it would flow.
I looked at my long, long email full of self-justification and realised: I didn't want to change the order simply because it meant more work. After a short bout of internal wrestling I deleted the email and wrote another, shorter one. You're quite right, I wrote to my editor. I'll do it.
And I did. And it was better.