The idea is the values in .env files can be configured via environment variables, while checks.yaml is for things that can be hard coded.
In this case it's a bit moot because the yaml file works like a database, but when you deploy this using, say, Docker or k8s, you can use a different method to configure environment variables and skip .env files.
In this case it's a bit moot because the yaml file works like a database, but when you deploy this using, say, Docker or k8s, you can use a different method to configure environment variables and skip .env files.