And yet, if you have two tasks that each take 1 hour, and only 90 minutes until the deadline, only one task will be completed by you, regardless of quadrant, and you will then be reminded that priority is singular.
TFA is about non urgent important tasks that you want to show incremental progress on. If there are multiple of those then those short bursts of works actual work can be eaten up by context switching, reprioritization, scheduling, etc.