Pro tip: spent 4 hours on a crown molding cut in a 1920s Denver house before realizing the ceiling was the problem
Checked my miters, my bevel, even swapped blades twice, but when I laid a straightedge across the ceiling it dipped almost a half inch right where the crown sat, so I ended up planing a shim to match the sag instead of fighting the saw, and now I always check that before I even set up the miter, anyone else learned that the hard way?