There are situations where actionable data is required within Salesforce to drive workflows, increase user productivity or to aid in reporting. The solution is sometimes that a roll-up summary field is needed, but that is not always possible. Some scenarios where roll-up summary fields cannot be used include:
- Custom objects with lookup relationships
- Filter by Formula rather than Static Criteria
An example of this would be the need to count the number of open Projects (custom object) on an Opportunity that have not yet begun but have a start date(kickoff) that is less or equal to Today.