Did you spend $20 on overpriced bed glass yet still find little quirks in the first layer of your print? Got your bed corners dead perfect and still got an issue from print to print? Try this test to see if there is variance in the glass. This test will also allow you to make adjustments during the print if you have a toolless setup like I do (thumb knobs recommended for ease of the tiniest change) I have found this to be a great asset. Watch the print width of the first layer print to see where your problem areas are and adjust as it prints. No need to let it go to the end. the first layer is the important one. Let it run to see problems in your retraction and restarts.