There's a horizontal offset, too, which may vary through the game.
FWIW, I use a homemade Paper Putting Pal, a scale divided by 10 and printed from a spreadsheet, glued to the low screen frame. Have to move the game windows a few times through a game.
For other shots, the official scale is good enough for me. It's difficult to calculate the yardage to the number due to the nonlinearity of shot length. I might improve by more diligence, but for me, it would smell too much like working at a computer then.