I currently work in legal/accounting. We do plenty of work in crunch periods varying between 12 to 15 hours a day, including or excluding weekends.
People lose effectiveness within a week at that volume of work. Consistently. They become forgetful, need things re-explained to them, act irritably, produce work that needs additional levels of revision, etc.
If the work is largely rote, that might be acceptable; perform an extra 10% work to quality control the 50-75% surplus in gross work product. If the work is strategic or synthetic, it is often not.
Over time, however, small performance degradations turn into health complications and morale problems. This is intentional. In high churn industries, individuals who are at the top of the ladder prefer that those they're leveraging lower down perform more work, leave before their positions are threatened, and use the corrosion of their health as a shield against the ambition of entry-level staff.
People lose effectiveness within a week at that volume of work. Consistently. They become forgetful, need things re-explained to them, act irritably, produce work that needs additional levels of revision, etc.
If the work is largely rote, that might be acceptable; perform an extra 10% work to quality control the 50-75% surplus in gross work product. If the work is strategic or synthetic, it is often not.
Over time, however, small performance degradations turn into health complications and morale problems. This is intentional. In high churn industries, individuals who are at the top of the ladder prefer that those they're leveraging lower down perform more work, leave before their positions are threatened, and use the corrosion of their health as a shield against the ambition of entry-level staff.