According to TFA, programmers at Amazon are required to be on call for a full week at a time. More programmers could mean sparser on call shifts, but it could also mean shorter on call shifts -- i.e. instead of going from one week every two months to one every eight months, go to two or three days every two months.

Being effectively at work 24 hours a day for seven days straight sure sounds like a recipe for burnout to me. As TFA notes, these people aren't doctors, the only thing that happens if a glitch takes two hours to fix rather than one is that Amazon loses some money. Amazon naturally would prefer not to lose that money, but its workers presumably would prefer to be able to sleep too.