A thread on one of the Internet forums reminded me of an interaction I had with a fellow a couple of years ago. His room was just under 10'X10', HO scale, double-track mains, transition era. Not a huge space, but workable.
Then he told me about his standards: only #8 turnouts would be permissible, along with a 36" minimum radius. His reasoning? It would be more like a "real railroad" and he wanted his layout to be recognized as uniquely realistic.
Okey-dokee. But one doesn't have to be a very experienced designer to see that there is darned little straight track left after placing 36" circles around a 10X10 foot space.
I suggested modulating his standards -- perhaps one scene with broad radii and turnouts and then using more compact standards elsewhere. Nope, that just wouldn't do for him. We both recognized that I wasn't the right person for the job and he continued his quest for a designer who could alter the space-time continuum.
Layout design standards should not be status symbols. Broad curves and #8 or larger turnouts look great – but in the more modest spaces typical of most model railroads, they create the need to significantly reduce the number and size of other layout elements possible.
If reducing operating potential or the number of railfan scenes in exchange for broader curves and turnouts is an acceptable trade-off, more power to you. But as John Armstrong noted, too large a minimum radius can be just as deleterious to a design as a minimum radius that is too small.
Standards should follow the concept, purpose, and space available for a layout, not lead them. That's why I hate to see folks with more modest spaces declaring #8 or #10 turnouts as their sine qua non even before developing their overall vision for the layout.