The first day of your career at McKinsey, you learned about the concept of “So what?”. It meant asking yourself what the real point of a chart full with analysis was, and writing that down as the title.
A so what should be meaningful, and not simply stating a fact for example instead of “We are making a loss in France”, maybe it should read: “It is time to leave the French market”
Once you established what the so what of the chart is, you could then go on an cut down any facts, data, or analysis that was not essential to make the point.
If you identified the key messages correctly you would be able to understand a document by just reading the headlines, the content of the slides just backs up what the title says.
A useful day-one concept, I still use it pretty much every day.