The straight curtain rod will need a shower or bathtub that is design in three-wall space only, even if it can be install in regular space, it will spend a lot of space that can be useful for other things, so it is not efficient. However, with L shaped curtain rod, you can install it in a spacious bathroom or the small one, as long as the shower or bathtub that you want to be curtained is placed near the wall because it needs to be installed by attaching each end of the rod to the wall. Architecture.