Interesting view points by everyone. When I got back into the hobby 15 years ago, I was all about semi-scale. As scale began to dominate my tastes, About 13 years ago, I began selling off the semi-scale ( except for my original 027 stuff from childhood ) and reinvested in scale. I've been buying mostly scale ever since ( with exception of my Aerotrain set and Y6b mallet )
My layout is approximately 17 X 6 ft. All curves are covered by tunnels.... either mountainous or a city above the tracks. The tunnels hide the ridiculous overhang of my scale GG1s, J class, and long passenger cars on curves ... especially the 042. Although I run 18 inch passenger cars, I assemble short passenger consists ( 2 - 3 cars ) which makes the trains look ascetically proportional to the layout. Sometimes I run 18 - 20 car freights .... having tunnels at both ends of the layout give the illusion of an even longer train, due to the train stretching from inside one tunnel to the inside of the other ... especially when running at slow speeds.
As others have said already its all up to you and how you view your railroad. There is no definite way of playing trains. There are as many ways to approach this hobby as there are hobbyists. That's one of the things I love about it all!