I've never seen it. But of the millions of times players have played more than 5 games straight, it's bound to have happened.
It's bound to have happened in the Millions of times players have played that a player has recorded 100+points and 100+ rebounds....
That's the logic you are using, FYI
Unless somebody can post a link proving otherwise, I'll have to assume 5 games of 8 assists EXACTLY in a row, is the longest stretch of consecutive games with 8 assists EXACTLY.