Amen! He hits the line with punch, and it takes 3-4 guys to bring him down which means at least one of them needs to sprint back to the line, become the A-defender who needs to set the line speed for the next tackle. If he finds his front, he creates qptb for the next tackle. In other words, he makes opposition middles work, which leads to fatigue, and opportunities around the ruck.
And having him on for 10-12mins either side of the half means Benji's explicit instructions are to keep working hard in defence for that period. No need to think of the long-game and conserve energy. Rip in, do your job softening up the interchange oppo mids, and then get-off.