I use this simple model to test my plates. The example shows issues with the build plate when it's been in use for just a couple of times versus alcohol-cleaned plates. These small issues can ruin the whole print from time to time.

And this simple model (just one layer!) helps quickly understand where the problems are and how big they are. A real eye-opener for me that helped me understand when additional cleaning is necessary and when it is not (hint: alcohol clean is a MUST with expensive quality prints).