Time Pattern: Task Dovetailing
All else being equal, a project with hard deadlines, or a rigid set of milestones to meet, is automatically a higher priority than a project without. Even as a project manager in a large academic institution, I found myself having to remind management of this fundamental math. To give a clear example of the trade-off being considered: if a missed regulatory deadline results in fines and possible litigation, it may trump new product development.
This is easier to conceptualize at the more concrete level of tasks. An easy pattern to recognize here: pairing a more rigid/higher priority task with a softer/lower priority task will allow the higher priority to flex against the lower priority task if needed. If we have prioritized our time within a uniform structure, the decision, for example, to move the lower priority later in the day and displace an even lower priority task, or to simply try again in the same time slot tomorrow, is straightforward and informed by other decisions made about the structure of your working time.