6 pucks would be a lot of pucks for a single system. I believe 5 is the limit, and even that is more than most people should have. There's a single 5GHz channel used by all of them, so having a lot of them doesn't necessarily help, and it can end up making things worse. The nodes will select a path through the mesh that provides the fewest hops to the destination (for internet traffic, that is going to be the primary node – the one connected to your internet service). So, if a node can get through to the primary at all it will do that rather than going through another node that might be in between. Since WiFi will slow way down if necessary, most systems end up with star topologies. So, you want to place the primary in the center of your home and then place mesh secondaries no more than one or two rooms away from there. A wired secondary can be farther away, since it isn't using the mesh interconnect. People have even placed them in outbuildings.
All of that said, it is possible to build a system with a mixture of wired and mesh secondaries. Just be aware that a wired secondary will not be part of the mesh, so it can't act like a "base station" for a more distant mesh-only secondary. So, mesh secondaries will need to be placed according to the best placement advice (described above).
