This is such a case by case situation that you can only make very broad generalizations that might not apply, anyway.
For example, I know a guy who improved his bench press by 35# just by including a 100 rep triceps day into his WSB-derived template. And it was all isolation movements.
Another example of useful isolation work is rehab/prehab stuff. If doing an intelligent prehab regimen prevents even one injury, then you're ahead of the game.
On the other hand, I know a PL who improved his total tremendously by stopping his WSB style training and just hitting the big 3 powerlifts...2x weekly for squat and bench, 1x weekly for dead.