Most of the work in signage is the setup: choosing the content, arranging the playlist, deciding which screens it plays on. Once that is done, you are finished. Delivery takes over from there, and it runs without you.
The moment you upload a file, Screenly gets it ready in the cloud. It checks the file is valid and, for video, re-encodes it so it plays cleanly across every kind of device in your fleet. That work happens once, centrally, before anything is sent anywhere.
From then on, your screens look after themselves. Each screen checks in with Screenly regularly, notices when something new is waiting for it, and downloads it in the background while the current content keeps playing. You never push content to a screen by hand.
Change your mind later and the same thing happens. Swap a file, reorder a playlist, point a label at a new set of screens, and every affected screen quietly picks up the change on its next check-in. You make the change in one place, and the network catches up on its own.