Andrea Ames points out that Jakob Nielsen has been talking about this notion for years: "Progressive disclosure is the best tool so far: show people the basics first, and once they understand that, allow them to get the expert features. But don't show everything all at once or you will only confuse people and they will waste endless time messing with features they don't need yet."
For information, provide just what they need where they need it.
It assumes a "competent" to "proficient" performer, not novice, not expert. If you put text in the UI aimed at novices, that text will be there "forever."
You reduce complexity by revealing only the essentials for a current task in the UI, and the offer more as users advance through tasks.
Layers build on each other. Progressive disclosure reveals information in an ordered manner. It provides only the necessary details for the context. It provides information that's necessary, not to simply create information to cover everything. We are fixated as an industry to writing information for everything. Don't repeat information. For example, don't repeat labels in hover text.
Doing this right means a fundamental understanding of user goals. That's hard work.
The process of helping users reach their goals is "a guided journey, not a scavenger hunt."
Design for the absolute best experience. Then when you have to negotiate what you can do, you'll know what the most important things are.
Job #1 is the user task. So we should be writing user task oriented content.
At IBM, progressive disclosure doesn't begin with writing. It's first about making the UI clear. And if it's going to take a lot of words to describe it, it's probably wrong.
Customers never read documentation. Reading documentation is never a business goal.
Goal: think more, write less.