If I have the choice I want a rested doctor working less than 48 hours per week, even if that's "less productive" than the same doctor working 70 hour weeks.
Anyone working an 80 week is absolutely less productive than two people working 40 hour weeks, even taking "communication overhead" into account.
Anyone working an 80 week is absolutely less productive than two people working 40 hour weeks, even taking "communication overhead" into account.