What testing methods can help you evaluate the efficiency of progressive disclosure?

• Moderated and unmoderated usability testing: This technique involves observing users in their natural environment or laboratory conditions. A moderator usually doesn't ask any questions unless users get stuck and need help. While users are performing a task on their devices, the moderator searches for friction points — areas that can be improved.
• Contextual inquiry: It's a combination of observation and user interviews. Firstly, a moderator interviews participants about their experience with a product/feature. Then, users perform a task on their devices in their natural habitat and context of use, while the moderator observes and asks questions along the way. It's a fantastic method to test what users say about a product and what they actually do when using it. Commonly we conduct contextual inquiry during the early discovery stages for a new feature or product.
• A/B Testing: This type of testing is about comparing two or more versions of a page/screen to see which is most effective and less confusing.^[1]

Other less expensive methods include guerilla testing, session recording, phone interviews, card sorting, etc.