Question

Is there any less redundant way to do this?

resources :tournaments do
    resources :commitments,     controller: "tournaments/commitments"
    resources :constraints,     controller: "tournaments/constraints"
    resources :entries,         controller: "tournaments/entries"
    resources :buildings,       controller: "tournaments/buildings" do
        resources :rooms,       controller: "tournaments/buildings/rooms"
    end
end

Answer 1

This is the convention for nested resources. Here all of the controllers are still in the app/controllers directory.

resources :tournaments do
    resources :commitments
    resources :constraints
    resources :entries
    resources :buildings do
        resources :rooms
    end
end

You generally only use directories for your controllers when you need namespacing, like:

namespace :admin do
  resources :users
  root :to=>"dashboards#admin"
end

#/admin/users