Sometimes geometry favors circumstances. In my case, the brick wall in my train room was a bit longer than 10 feet, so a GS 6-foot section and a pre-cut 4-foot section fit nicely with a 2-foot section "left over" - which I'll probably never use.
When I learned how to install the split connections for rail alignment, that process was easy to perform. The result -- shelf alignment was "right on." The center rail matter wasn't a issue for me. Vertical spacing of the rail sections was "pre-ordained" by the brick mortar joints of the wall - no need for measurements. Photo of the installation is attached.
Bonus: the stout mailing tubes from GS were reusable and "recyclable." I cut them to a designated length and then sent my long-length Lionel O-gauge track sections to e-Bay auction buyers.
Mike Mottler LCCA 12394
mottlermike10@gmail.com