Push (Button) Switch Symbol
This is a bit dependent on how you work with the EDA software you're using. If you prefer to show on the schematic exactly where each pin goes, you need four pins on the schematic to correspond to the four pins on the physical switch. Personally, I prefer to show this explicitly on the schematic, as here: 



As to where it makes more of a difference, consider the bussed layout below from an NKK datasheet.