Under what conditions should I replace the spark plugs on my Audi A5?

I have an Audi A5 with about 50,000 miles on it. I'm wondering if it's time for me to replace the spark plugs. What are some signs that the spark plugs need to be replaced? Should I replace all of them at once or just the ones that are showing signs of wear? Also, should I stick with the manufacturer's recommended spark plugs or is there a better option? Thank you!

It is generally recommended to replace spark plugs every 30,000 miles. However, if you have hit 50,000 miles without any issues, you may not necessarily need to replace them. Signs that your spark plugs may need to be replaced include decreased fuel efficiency, difficulty starting the car, and rough idling.