If you're putting two or more units together, there will normally be eight-pot stacks between adjoining buildings: the four pot stacks are usually found at the ends of a row and on the rear extensions. The Chimneys are pre-set to a nominal height, but there's room for variation: lowering or even raising the stacks is quite possible and can provide interesting changes in character.
The screenshot shows CH8Ps in position as part of a completed terrace.