This is a question of the "time responsibility" of the system.
If you shift left, i.e. a user is responsible for the time tracking, it means:
- user uses "internal" calendar (in his/her mind)
- user has full control over labeling the search results
- user sets time-related labels to the search results, according to internal calendar
- user can be inconsistent in time-related labels, but he/she is certain about labeled content
- user expects to see exactly the same documents, which were saved under "yesterday" label
The example is a blog post named "The book I've read yesterday" -- yesterday is label but relates to fixed content
If you shift right, i.e. the system is responsible for time tracking, then:
- the system provides time-related labels, like "yesterday", "last week", etc.
- this labels are the alphabet of the system and user doesn't create it, but just uses it
- label meanings are consistent, i.e. "yesterday" is always the day before today
- most users rely on the system's alphabet and expects to see yesterday results under "yesterday" label, etc.
The example is organizing History in browser, where the browser applies "Today", "Yesterday", etc. labels to the list of items. These are the labels which relates to non-fixed content (today's Today is Yesterday on next day).
To make a system more usable and to support user in time-related activities,
- allow user to label the results, in most cases they will give more semantical names, like "books on photography", "bicycle repair", etc.
- use calendar control near these actions to help user to reference to date and time if time tracking is needed
- auto generate and apply to the saved content metadata which includes the date and time information
- provide tools to handle with data-related content, like search, filtering, etc.