A mesh router with one node is enough for most homes. This will help you extend the mesh network in one direction from the mesh router and can bypass most obstacles. Most homes are unlikely to benefit from three nodes unless each node is rather weak, which is true of budget mesh systems. Homes that are large (we'd say 5,000 square feet or more) can benefit from a second node, for a total of one mesh router and two nodes. This can also be helpful in asymmetric homes  or if the mesh router can only be placed at the edge of a home rather than somewhere central.  Some systems even support three nodes. We were not able to test any such systems for this guide, however, and our test home is far too small for this number of nodes to provide a difference in performance or reliability.