We O-types run them "close to the edge" because we're much more manly - even the women - than the effete types in the wee junior scales. They invented the phrase "living on the edge" just for us.
OR:
It could be that we only have so much room and the stuff we run is just so big that every
32nd of an inch counts.
This (poor) photo shows the plexiglas that I installed years ago on my layout on all "open edges" of my layout. This applies to straights and curves. The locos never fly.
(Note the exquisite masking tape switch machine reinforcement in the foreground; it was wobbling, so "temporarily..." And the steamer on the ground behind the Centipede!
Always a layout in progress, though "progress" never seems appropriate, somehow.)
