Love 531, its been a program I've always come back to after trying other things.
One thing I've noticed in the new book however is that the idea of using opposite lifts has, from what I can see, gone.
I've always doing my 5/3/1 sets with a lift, then used the opposite lift for things like my BBB kinda stuff. So Squat 531 then Deadlift BBB.
It doubles the frequency of each lift and I felt I could give more on the second lift that way.
The only place I see this mentioned so far is at the very start with the original BBB program. From what I can tell its not mentioned elsewhere. But I have seen it mentioned that you shouldn't do it. And with a lot of the program layouts being fullbody, it obviously doesn't apply there.
Does Jim now advocate against doing this? Its not made clear in the book whether you should just keep all your squatting to squat day, all your benching to bench day etc.