When setting up a training plan in HackEDU, you had the option to roll training out to your learners with no time limit OR you can choose to set a time based or date based due date.
Time Based Plan
Time-based plans have a duration attached to each phase, so when a new user joins your organization, they start from the beginning of the plan and work through it in the number of days you specify.
These plans are recommended for most organizations, where a compliance date doesn't need to be met for the organization.
Date Based Plan
The phases of a "date based" plan have a fixed start and end date associated with them.
Date based plans are great for organizations who are trying to meet a compliance requirement by a specified date, or who just want to make a certain set of lessons available for their developers for the entire year.