This setting controls where NCrunch should store its project configuration files. Normally, these files are placed adjacent to their source (.xxproj) files. This setting allows all NCrunch project settings files to be stored together in a separate directory declared relative to the solution (.sln) file.
Normally, you should not need to alter this setting from its default. NCrunch project settings are targeted specifically for their projects and should travel with them. Where projects are shared between solutions, their settings should usually be shared with them.
Where this setting can be particularly useful is when you are using NCrunch independently on a solution shared with others that do not use it. Placing the project settings files in a fixed location can make it much easier to exclude them from source control systems and avoid clutter for others not using NCrunch.
The value for this setting can point to either an absolute directory path, or a directory relative ot the solution (.sln) file.