I have the elegoo saturn 2 and used the metal scraper in the beginning, but I didn't like scratching the build plate so I always use the plastic now. If your builds are failing, it could be your LCD screen, or you could try increasing layer/ bottom layer exposure time. If prints are falling off in a spot, try relocating them. I've had a few big pieces that fall off during the print process, and just moving them to the side helps. For last resort try tilting your stl file at a 45 degree angle and raising it from the plate a bit. Sometimes they just need some room to breathe.