Davide,
If 4 different designers do 4 different Chapters on the same ToO, and these Chapters have very different maps between them (from the designer's perspective, then this may be "a minus" for the whole effort.
A prototype may include general directions for the map designers in order to keep a minimum homogeneity to all related maps.
But you may continue with your map designing; just keep in mind that maybe in a later stage you might do a small "lifting" (by editing) to some small details of your map.
ciao,
Pyros
