While you should consider when to build what facilities, the focus on where to place them is generally inconsequential. The changes here emphasize less focus on meticulous base building.
In the first game, it was important to build facilities adjacent to ones that would provide bonuses to one another such as Generators providing bonus Power or Workshops refunding materials, also there were 24 spaces to build in where XCOM 2 has cut that number in half and overall reduced the number of facilities you need to build. XCOM 2 made significant changes to base building in that it is much less complicated when considering where you should place everything in the Avenger.
