Ease of understanding and adds context

Use common scales when showing several charts on the same page.

For ease in comprehension

Include annotation as close as possible to data on chart to which it refers.

Less clutter

If all charts on a page use the same Y-axis unit, the unit of measure can be noted at the top of the page.

Faster understanding

Slides should be as self-explanatory as possible.

Guideline

Rationale