You should typically deploy access points a minimum of 50 feet apart. This is in areas where there are walls, rooms,etc In open space like a warehouse, it is typical to deploy access points every 100 feet due to the open nature of the environment. The 50 feet requirement could turn into "every other room" if the walls are made of concrete.
Long story short, you need to possibly do some survey to see what the penetration of the RF is in your specific environment to get a real idea of what to deploy how. 50 and 100 are just back of the napkin starting points for your survey to determine how far to actually put them apart, because every environment is different.