personally I like to take my time when I shit, so sitting is preferred.

anyways, most toilets in the US are fine, but occasionally you'll find one with a high water level and then *splash* you get surprised with a wet dick. Or if you have to lean over to pick something off the ground--not that there are often things that you want to pick up off of a restroom floor--that gives you an extra inch or two, you may find yourself with a wet dick.

Through experience I have made it a habit to notice the water level, and adjust where my dick hangs accordingly.