Can be closer to 40% in my experience with Intel when things are memory/cache bound (i.e. one thread is regularly stalled waiting for data), and I've seen above

Can be closer to 40% in my experience with Intel when things are memory/cache bound (i.e. one thread is regularly stalled waiting for data), and I've seen above 55% in some cases with AMD's Zen microarch's SMT (Zen3).