How I work
Audit before changing. On an inherited site I find out what is actually running, what version of everything, what has been hacked in, and what will break if I touch it.
Bulk operations get dry-run first, applied in a way that cannot half-complete, and verified by reading the data back afterwards. The verification is not optional, because a write can succeed while a cached response keeps serving the old value and makes it look like nothing happened.
And everything gets logged: what changed, which files, which database rows, what was deliberately left alone. If I disappeared tomorrow, the next developer could follow it.