Redmine

Christoph Klesser wrote:

As of #594, subproject nesting depth limit has been removed. Good idea in general, but for some organization it makes sense to define a depth limit - either by generally limiting the depth in the administration settings or by adding an option like "No subprojects allowed" in each project settings.

IMHO it would be an absolute no-go to generally limit the nesting depth of projects.
I also replied to your thread here: Limit subproject nesting depth