I've tried a lot of calibration tests and temperature towers and there are some really good ones here on Thingiverse but really at the end of the day, all I really need to know is the answer to a few questions:

1. Will it string?
2. Will it bridge?
3. Will it print an overhang?
4. Will it print a fine point that won't snap when I press on it?

I could (and sometimes do) print a large tower that tests a whole range of temperatures and other things in one print, but if I'm going to be near the printer it's usually faster to zero in on the perfect settings by starting with the recommendations on the label and then tweaking things from there over a few iterations.

This model has a couple of sharp points that are reasonably difficult to print cleanly and that tend to string with poor settings. It has a (just under) 20mm bridge. And it has a 70° overhang that is right about where I find that dialed in settings start to struggle on my printer. It also has a 20x20mm base in case I want to check x/y calibration. And best of all, it typically prints in under 10 minutes!

Is this a substitute for other more detailed calibration models? Probably not. But if I'm dialing in settings for a new filament, I find that this is just the trick!

Let me know if you find it useful too!