Back at McKinsey in the 1990s we would write a long-hand sentence, or a "lead" at the top of every slide (similar in length to today's 140-character Tweets. This sentence would give you the message of the chart and you could get the whole story by reading all the leads in a document, without looking at the exhibits below.

I am re-discovering the sentence recently.
  1. In some presentation designs, I switch to a slide template with a 2 line title, creating space for longer sentences at the top of a slide.
  2. Certain thoughts or concepts are just too complex to shorten to 2 bullets of 3 words each, so I am just writing them out.