I've worked with people who burned out and had to take time off days before deadlines doing demonstrably less than others who worked 9-6 and made sure it matter

I've worked with people who burned out and had to take time off days before deadlines doing demonstrably less than others who worked 9-6 and made sure it mattered. Delegation is certainly part of the problem, but I think there's a point at which people start buying into the mythos and cargo-culting a 'no work/life balance successful startup', which is really damaging.