As I was approaching construction there were certain aspects which I desired and some I wished to avoid. It started out as a modest wall mounted "L" along two sides of the basement with a dozen or so turnouts and a box of track. I soon saw how I could extend it if I removed or altered certain obstructions plus cut a few holes in a couple of walls. In the process I inherited a real nice peninsula from a friend's widow which I could use if I moved the water meter . Water meter moved.
Another opportunity presented when I discovered a non weight bearing cinder block wall. Wall gone. None of this was apparent at the onset. Then there was this large hot water tank which constricted yard development, enter a Rinnai tankless water heater. Then I found a way knit into the layout some display modules I had built for shows. The pike just grew like a tray of mushrooms.
The initial sketches were totally blown by the wayside so I wound up using an assortment of cosmetic, spiral easement and fixed curve and tangent templates. Clamping the templates in trial and error placement to yield best grade and clearance over fixed fingers jutting from the walls produced the parameters for the module construction needed to provide an appropriate setting.
I now have this over built pike along the lines of what over time has been described as "The monster in the basement"
There is just something lacking in two dimensional pencil lines or computer lines which fail to tell the whole story.
Your mileage may vary...