I have spent more of my life than I'd like to admit kneeling at eye level with a print bed, sliding a folded sheet of paper under the nozzle and arguing with myself about whether it "felt about right." Front left, front right, back, back again, repeat until the first layer either smears or refuses to stick. The four-corner dance is a ritual, and like most rituals it's mostly there to make you feel you've done something.
The thing nobody tells you when you start is that the bed isn't a plane. It's a slightly warped sheet of metal or glass that flexes when you tighten the screws, and the four corners you've so carefully levelled tell you nothing about the bulge in the middle. You can get all four corners perfect and still have a first layer that's too high in the centre. That was the bit that finally broke me.
I fitted an inductive probe and turned on mesh bed levelling in Marlin, and the war didn't end so much as relocate. Now I argue with probe Z-offset instead of corner screws, which is at least a single number rather than four interacting ones. But the first layer is consistent in a way it never was by paper, and I stopped throwing away the first attempt of every print. If you're still doing the paper dance and it's stealing your evenings, a probe is the single best thirty quid I've spent on the hobby. The war continues, but I'm winning more battles.