Inspired by Guy Kawasaki's famous article "10/20/30 rule of PowerPoint", I have developed "The 10/20/30 rule of Documentation".

It should be "The 10/20/30 rule of Word", but there are many people who don't use "MS Word" as their documentation tool, so I had to generalize it.

So, what is the rule? It is to ditch PowerPoint, and go for Word (or any documentation tool). It goes like this;

10 slides

If your presentation is longer than 10 slides, use Word to document it.

20 minutes

If it takes more than 20 minutes to present it, make a separate Word document to provide details to the PowerPoint slides.

30 point font

If you have to use font size smaller than 30 pt, use Word to document it.

I don't understand why some people stick with PowerPoint slides to make 100 pages, newspaper-size font materials. It is very painful to read, not to mention how painful it is to edit them.

Use Word for supplementary documentation for extra explanations, data, and manuals. You can take advantages of several features like auto-generation of list of contents, styles, auto-numbering of footnotes, indexes, etc., which PowerPoint does not provide.

PowerPoint for Presentations, Word for Documentation. Simple as it is.

I hate people breaking style guide, especially under working in team environment or need to collaborate with two or more people. Someone needs to set up strict style guide in corporate work environment, so that everyone can communicate accurately and efficiently.

There needs to be rules between team members. For example,

e-mail / email / E-mail
online / on-line
U.S.A. / USA
use of "&" (for "and"), "/" (for "or"), "#" (for "number")
use of commas, semicolons, colons, hyphens, etc.
use of pronoun - "You", "They", "I".
and many others like company logo, brand color, fonts, etc.

There may not be correct answer or usage, but everyone needs to follow one rule, if they work as a team.

There are style guides available online, so  look them up.

Wikipedia style guide (more practical style guide is Wikipedia Manual of Style.)
AP Stylebook Online

If you need reference on your desk, there is a book for you.