We already talked about the High Impact Tasks in the Getting Started section. You can refer to it for more details.
The High Impact Tasks list represents what you deliberately want to accomplish this week. Generally, they come from the top items in your Backlog but can also come directly from the Inbox.
Ideally, you want to make progress on each of your objectives, so you would want to have one task per objective. Additionally, you don't want to neglect any role, so you would ensure you have at least one task from each Role.
Don't overcommit. The HIT list is a contract with yourself. A commitment you make with yourself. If you start breaking this commitment on a regular basis, the HIT list will lose of its value. Respect your HIT list.
It is better to have fewer items than too many.
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