In order to Keep It Simple Sailor (KISS) there are only two types of basic building blocks for a PBS-style town: full and half-blocks.
made by someone else.
It is possible to build wider streets or even to create a public square that is virtually all filled with cobblestone. The four-wide is a minimum to make sure there is some sort of street network through the whole town and to make some space between buildings.
Building a block can be quick and easy especially if you have some of the Castle sets released in recent years like the Medieval Market Village (10193-1) and the Mill Village Raid (7189-1). The buildings are easily modified to be part of a pirate town and since they are mounted on bases they can be easily removed if needed.
The question often comes up if it is acceptable to encroach on the specified "streets".
The short answer is NO. The streets are designed to be very narrow already and filled with people, animals, whatever.
The longer answer is SOMETIMES: if you want to create building that sticks out over the street ABOVE THE GROUND FLOOR then by all means. Just do not cross the line from the edge of the baseplate. If you do that you are encroaching on your neighbours space and this may create problems.