Hello Spookman. Lester pretty much summed it up with his reply. For instance, on my layout which will be 12 feet long, by 2 feet wide, I have incorporated quite a bit of activity. I have 6 seperate industries that recieve goods by rail, as well as an interchange track, a small 3 track yard and a pier facility that has 2 tracks with 12 spotting locations. A facility such as a pier warehouse offers plenty of switching opportunities to keep me busy. All this is done on a 2x 8 linear shelf layout. I have just added another 2x 4 section to it, but it has no scenery at the moment. I should be able to add a few feet to my 3 track yard, and another industry or two. One advantage of this is that I can keep adding on to my layout as more room can be found. Also, I like how it puts you right up close at trackside. I also find by adding small portions at a time, you can get things accomplished more quickly by only focusing on a small area at a time. These are only my observations and opinions on what works for me. There are many other ways of doing things and lots of great layouts on this forum where you can see all different types of layouts in many different styles. Hope that clears things up, and good luck.
Stuart