25% is if the organization is ultra efficient. I think most organizations other than select FAANG/Stripe are at 75%+. I think pmarca quoted the number to be something like 1:4 which makes the efficiency at 25%, 75% dead weight. FAANG is probably at 50%.
The good big companies are overstaffed by 2x. The bad big companies are overstaffed by 4x or more.