Please note that this test assumes a level bed. Prusa printers have an automatic bed leveling mechanism that calculates variations in your bed height, but other printers may require manual leveling. If your bed isn't level, this test will probably give flawed results.

This is just a single layer (0.1mm) height rectangle that can be used to fine-tine your extruder nozzle height.

Set your Live Z-Adjust to the desired level and print this rectangle. You can adjust z-height as the rectangle is printing, no need to wait until it is finished. That is why I have made the rectangle so long.

If there are gaps in the print, lower the nozzle 0.05 mm at a time until there are no gaps.

If the nozzle is scraping the print, raise the nozzle about 0.025 mm at a time until it is not scraping.

Once your first layer looks good, you can fine tune to within about 0.012 mm until you are satisfied with the results.