Illich's Law
Beyond a certain threshold, working more hours decreases productivity.
Tiny Summary
Illich's Law: "Beyond a certain point, working more hours decreases productivity." There's an optimal work intensity—push past it and output declines.
The Law
Ivan Illich: After a certain threshold of work intensity, productivity becomes counter-productive. Burnout kills output.
The Curve
Productivity
↑ /\
| / \___________
| / \___
|___/________________________\___→ Hours Worked
↑ Optimal (40-50 hrs/week)
Sweet spot: ~40-50 hours/week. Beyond that: Diminishing returns, then negative returns.
Why It Happens
Cognitive fatigue: Brain needs rest. Tired → more bugs. Exhaustion → poor decisions.
Physical limits: Sleep deprivation compounds. Health degrades. Immune system weakens.
Motivation collapse: Burnout kills intrinsic motivation. Resent work. Quality plummets.
The 100-Hour Week Fallacy
Manager thinks: "100 hours this week → ship faster"
Reality: Week 1: 100 hrs, 60 productive. Week 2: Exhausted, 30 productive. Week 3: Burnout, 10 productive. Week 4: Out sick, 0. Net result: Less done than sustainable 40-hour weeks.
Optimal Work Patterns
Sustainable: 40-50 hours/week, 8 hours/day with breaks, weekends off
Crunch (rare): 60-70 hours for 1-2 weeks max, must be followed by recovery, unsustainable long-term
Research
Stanford Study: Productivity drops sharply after 50 hours/week. 60 hours/week = same output as 40. 70+ hours/week = less output than 40.
Key Insights
Working more ≠ producing more (after ~50 hrs/week). Burnout destroys productivity. Sustainable pace beats crunch long-term. Rest is productive (brain needs recovery). Managers: protect your team from overwork. Related: Sustainable Pace (XP), Technical Debt from Exhaustion.