> provided that you also write unit tests and do code review
Not necessarily. Imagine submitting a patch on 8 PM, when everyone has already been in the office for 10 hours. It has a glaring bug in a particular branch that's not covered by the unit tests in a way that coverage testing doesn't show, yet everyone is too tired to see that bug. Thus the patch gets greenlit and applied to production. Just as everyone is heading home to fall into bed, pagers start ringing because prod is on fire.
Not necessarily. Imagine submitting a patch on 8 PM, when everyone has already been in the office for 10 hours. It has a glaring bug in a particular branch that's not covered by the unit tests in a way that coverage testing doesn't show, yet everyone is too tired to see that bug. Thus the patch gets greenlit and applied to production. Just as everyone is heading home to fall into bed, pagers start ringing because prod is on fire.