If you are installing showers into a building, it is important that you take the privacy of future customers into account. Customers will be unwilling to use your facilities if they do not have adequate privacy. Instead of investing in communal shower cubicles, you should consider investing in more private single-person shower cubicles.
The typical size of a single person shower cubicle is 2000mm X 1000mm. When building, it is essential that there is a floor incline and drainage under the showerhead. This makes sure that there is no stagnant water lying around, which will keep the facilities clean and sanitary.
If you are thinking about installing communal shower spaces instead, you should only put these in facilities where privacy is not so much of an issue.