I've heard that, but I've never been able to determine if that was just rumor, word of mouth or factual.
I remember one year that Patriots were getting prime time games every single week and it was pissing Brady off and I was enjoying that it was pissing him off lol, I guess it messes with his sleep schedule, especially away trip prime time games.
My wild @$$ speculation, is that try to mix it up, but if there aren't good other options, and the tv people are really pushing them to do it, the NFL will do what the tv people want...
So I think the rules could apply to the NFL initial scheduling, and maybe not changes in said schemes. By that's my pure speculation, like I've said, I've heard of those rules, but I'm not sure I've ever heard that they're officially written down in some official rule book...
Which really doesn't matter because they NFL isn't following the rule book tightly anymore anyways... (PS, I've been saying that for weeks, I'm not bringing up anything with the WFT game with that comment... but that the refs seem to be trying to consistently follow what I assume the NFL telling them to follow, not nessarily the NFL rule book.