Here is my assessment of what is happening with the spread out of digital modes, at least here in the U.S.:
"Water holes" have been established by default, for PSK31, the most popular digital mode, and this tends to form the bottom of a "digital area." Then those of us who operate wider, more robust modes, tend to choose a frequency a bit higher, just outside of that narrower area. The RTTY hams tend to operate even higher, sometimes near the top of the text data portions although there can be a mix of modes at times. 73, Rick, KV9U
