For reasons unknown, the hobby defaulted short turnouts. I suppose it had something to do with the fact layouts used to be confined to 32 square foot chunks of space (4×8 sheets of plywood) and short turnouts let manufacturers sell more track per square foot. They also fit in with the sectional track systems of the train set era where the pieces were designed to be completely interchangeable. These track components are still widely available in multiple scales.
Pictured above is a turnout off the NS mainline in Richmond. I don’t know the frog number because I didn’t want to poke around on the tracks in a very public place. Needless to say it’s longer than a No. 6. I simply have a hard time picturing a quartet of Dash9s or a 2-8-4 tip-toeing through the typical No. 6 model turnout at track speed, yet that is exactly what happens on countless layouts. The rationale is that long turnouts take up too much space to be practical. I agree that a yard ladder of No. 10s in any scale will be a space hog but I disagree for other applications.
When people are going to great pains to wrap 600 foot mainlines around their layout space and default to Nos. 6-7 turnouts for mainline situations I have to wonder. Wouldn’t a No. 10 look so much better at the end of those 18-foot long passing sidings? You’re going to quibble over a few cars of lost train lengths over 10 scales miles of track in HO?
The N scale community could lead the way for the rest of us. They have the space ratio to really do flowing prototypical track work justice. A No. 10 mainline turnout could be the minimum and Nos. 12-15 are not unreasonable to consider in that scale.
However, if anything bigger than a No. 8 is considered as outrageous in HO or even N scales, it must be a pipedream in quarter-inch scale and yet, P48 No. 10 frog castings are readily available. Go figure. For much more about modeling track and turnouts, see our book Detailing Track.