Diary Studies are helpful for learning about the change in the contextual experience over time.
Tracking how people deal with a lengthy process, that might last a day or more.
Understanding what encourages people to make a certain effort.
Discovering how the product/service corresponds to the user's needs.
Assessing retention.
Uncovering all engagements over a specific timeframe.
Collecting general knowledge about people's behavioral patterns.
Discovering how the users go through/approach specific tasks.
Capturing mindsets/expectations/moods, determining the way in which the user experience was framed.
It is relevant to conduct diary studies at any stage of the project when you are looking for understanding long-term behaviors.
What part of the day do people engage with a product/service?
For which purposes do users engage?
What encourages users to do certain things?
What do people think and feel before/during/after the engagement?
How learnable is the system? How loyal are people over time?
What is the typical customer journey?
What does the cross-channel user experience look like?
What is the overall experience of multiple service touchpoints?
The length of the study could vary anywhere from a couple of days to several weeks – depending on the objectives of the study, the accessibility of the user group you want to focus the study on, and the number of user groups that needs to be involved in the study.