Whats your normal 'first' or 'calibration' print?
Whether its the first time you use a printer, after a modification or repair or after changing to a new material, most of us do a test print of some description.
My personal favorite is Marvin, although I have done calibration cubes in the past.
:) :) :P
I do a cube because that way I can see if my x y and z steps per mm are correct. Then I usually do a marvin to test overhangs and small piece accuracy with the keychain part.