1st layer test is 200x220x.2mm and serves as my go to first print for any change on my printers to set proper z offset/babysteps and even measure to center the bed/nozzle

Extreme 1st layer just covers more surface area and is 215x215x.2mm to get a more accurate view of the bed and any changes to the flatness of the bed, inner rings are 10mm spacing out to the 100mm radius and outer rings are 20mm spacing out to the edges