I was such a bad developer that I realized I had to automate the re-running of parts of the system to find the bugs.
Of course, the code I wrote to exercise the code I wrote had bugs, but usually I wouldn't make offsetting errors.
It didn't fix all the problems I made, but it helped. And it helped to have the humility when trying to fix code to realize I wouldn't get it the first time, so should automate replication