Don't end up overwhelming your audience. Too much content can yield bad results which is a digital signage fail. Content density refers to the amount of different content on your screen at a single time. If your viewers have a longer time to read, then it's ok if your content density is high. If your viewers are passing by and only have time for a quick glance then your content density should be low.
Think about how much time you have to reach an audience compared to the amount of bulletins you want to run. If you have a captive audience for 2 min, and bulletins run for 15 sec each … that means you have time to display 8 bulletins in that 2 min span.
The brain chooses what it will and will not store in our long-term memories. You want people to retain information so don't overwhelm them if they don't have the time.
Getting the reader's attention in the first two paragraphs is essential. Headlines should be short, snappy and entice the reader. Use imagery that helps draw the viewer in.