I honestly don't think that's something a player with a western grip should be bothered about, rather than just trying to hit deep with heavy spin - how often do you see Nadal, or guys like Fritz, Kolhreichber, or even Djokovic hit the ball flat? The only times they do i believe, is when the ball is very high and they can just hit the ball straight through the court without any arc, and they don't swing low-to-high when they do it - they use a different mecahnic and swing high-to-low to just hit as hard as they can straight through the ball.
I am myself bad at it, because i can't usually hit such balls with power, because im used ot hitting low-to-high and i can't usually get enough acceleration on this high-to-low motion that im not used to. But i guess if you practice it enough, it will become natural