Phototheca has the feature Live Album that works in a next way: you create a Live Album and specify a list of sources(folders) that are used to populate the album.
Since you have such an album is created, Phototheca does regular lookup(every few minutes) in those folders for new images. When new images are detected — the app imports discovered new images automatically and images appear in the library according to Live Album.
It does not depend on how many people update a network folder at the same time. Every running instance of Phototheca in your network does update from those network folders independently, every instance by its own schedule.
Read more: Live Albums