This is a set of tiny models (just 20 mm in diameter and 10 mm tall) that can be challenging to print, depending on the material and the settings. The advantage is that this test can take as little as 7 minutes or even less, and requires little material (the prints in the photo take about 1 gram), therefore it is ideal to validate changes to cooling setups without waiting for a large test object to print.
A cooling fan directed towards the printed object has two basic purposes. One: improve the quality of printed overhangs by immediately solidifying material before it can droop down. Two: cool down ‘short layers,’ i.e. layers so small that the material has too little time to cool on its own before a new layer is printed on top. This test is a compromise between both, although you can remove the ‘short layer’ aspect by scaling up the model and/or printing slower.
WARNING: depending on how you print them, these test models may warp excessively to the point where they will cause considerable forces on your print bed and nozzles. Monitor each print and be ready to abort if things go awry, or the ‘torture’ part may become all too real.
I tested in Slic3r with two layers and concentric 15% infill. Each model contains a hollow tube that prevents Slic3r from attempting to deposit infill in thin air for these specific settings. I should file a bug for this sometime…
If you want to check whether a particular cooling setup performs better than another one, find a set of settings where the old setup provides an almost-but-not-quite OK result on one of the test objects of choice (the lower angles are easier, if you cannot make them fail, try a larger angle). Then print the exact same file with the modified setup, and check whether it produces a better outcome.
For validating the prints, check whether the top surface is perfectly flat, and check the sides for blobbing.