If someone preaches to the choir, they talking about a subject or issue with which their audience already agrees. ('Preaching to the converted' is an alternative form.)
Well-oiled machine
Something that functions very well is a well-oiled machine.
x-raying machine|machine|x|x-raying
n., slang, citizen's band radio jargon Speed detection device by radar used by the police. The smokies are using the x-raying machine under the bridge!
An achin idiom dictionary is a great resource for writers, students, and anyone looking to expand their vocabulary. It contains a list of words with similar meanings with achin, allowing users to choose the best word for their specific context.
Dictionary of similar words, Different wording, Synonyms, Idioms for Idiom, Proverb achin