One of my problems is that I built this layout before DCC, as well as Just Plug, and retrofitting these features has been a chore, since benchwork and most scenery were already completed. Finding a location for light hubs was a problem, since they need to be easily accessible to adjust brightness, swap out plugs if needed, and extend the system. As a result, I mostly couldn't just attach them to the existing L-girder. For now, I'm adding scrap pieces of 1 x 4 to attach them beneath the fascia. I don't care if they aren't pretty. I gave up on open houses years ago. But I can reach them without bending over.
But even if I were starting from scratch, it would be something of a puzzle to find places to mount them and keep them accessible. They require a fair amount of space, especially in multiples.
One of the best features of the system is the light diffusing film. This does wonders for buildings that have the old incandescent sockets as well as Just Plug LEDs. Below is my new Bar Mills Rusty's Radiator Repair, which I built from the start with light diffusing film behind the windows and a stick on LED under the roof.
The IHC town house behind it has had light diffusing film retrofitted but keeps an incandescent socket from decades ago. You can't tell the difference. The building at left below has just had light diffusing film retrofitted but again, it keeps its incandescent socket. The electrical connection had come loose, but I reconnected it when I repositioned it over the last couple of weeks. The First National Bank at right has never had lighting and needs to have light diffusing film added as well. This will be a priority. In general, I've added light diffusing film to all my existing buildings, whether or not they're lighted, and all new building kits are built with it and stick on LEDs installed from the start.Finally, as I thought, I gained enough space for a new building front farther down Lake St by swapping Old Dutch with Robbins Opticians and narrowing the alleys. I'm now thinking about making this a City Classics art deco, which will have the full lighting feature installed from the start. But you can see I need to add this to the whole block.