Can we use vertical bar window grilles?

Can we use vertical bar window grilles?
This has more to do with common sense then Feng Shui.
For example, if one's grilles are casement windows; it does not matter that much if the window grille bars are horizontal or vertical.
However, if the one has sliding windows; then it makes more sense if the window grille bars are horizontal. Why? Pure common sense.
In order to open or close sliding windows, the most efficent grilles are those that are horizontal bars. This allows for swift motion to slide the windows unobstructed with horizontal grilles.
But if vertical grilles were to be installed, one may have to frequently remove the hands and place it into one or more vertical openings to fully open or close the windows.