In the printing world, if an item or color is printed to the edge, then a little extra should go beyond that boundary (bleed). This allows the cutter a bit of wiggle room during the trim process. At the same time, no item of value; text, logo, or page number, should exist within a close proximity of the edge, just in case the trim is a bit inside the margin.
The same is true of projected presentations for conferences, trade shows, and other large venue uses. Important content should not go all the way to the edge to allow a little extra overlap off of the screen. In the early days of PowerPoint, it was customary to require a ½” border where important content was not permitted. With uses of PowerPoint expanding beyond projected presentations; flip books, general thought collection, board meetings, this rule seems to have gone away. Due to the more sophisticated projectors of today, I would argue that ½” border may be excessive; however ¼” or more still should be followed. You never know when that little bit of space will prove advantageous.