A 210x220 0.5mm first 2 layers test. Usually when I print with 0.2mm layer height I do the first layer at 0.3mm so this would test the first 2 layers of the print, in the whole bed to see if there's anything unpleasant you might find printing close to the edges. This helped me a lot to check if the temp on the whole bed was uniform and if the adherence was all the same across the bed.