The issue being this: your muscles don’t give a damn physiologically when your form breaks. If your quads are the target muscle and your form breaks 5 reps before they are approaching true physiological muscular failure, it doesn’t matter. Well it does in that it means that your set of...
At rep 10, the low back fails, the set is stopped and the quads are still 4 reps from failure. Counting that as a “set to failure” is only correct for the low back in this case. The quads were nowhere close. In the effective reps framework, the low back probably got 4-5 effect...