Recovery from forgetting to add something is _much_ easier than recovery from adding some weird configuration file with plaintext private keys in it.
It depends. I've lost hours of work after wiping and recreating a repo that had accidentally gitignored a file I was working on, and I didn't notice until too late.
I usually have *secret in .gitignore and append .secret to any files with secrets.
It depends. I've lost hours of work after wiping and recreating a repo that had accidentally gitignored a file I was working on, and I didn't notice until too late.