"a necessary portion" is correct and usable in written English.
You can use it when you want to refer to something that is an essential part of something else. For example: "Exercising is an essential part of a healthy lifestyle, and an important necessary portion of my daily routine."
But I'm not quite in agreement: This week marked a significant point, not because of the act itself, but because of the consumption of that act (a necessary portion of justice, some would argue).
Try to remember that you don't have complete control over every hour of your day sometimes and that meeting an obligation such as being present for the unproductive meeting can still count as a necessary portion of your day.
" Because keeping solid time is so integral to playing drums, a metronome is a necessary component to at least a portion of any practice session.
In the northerly latitudes (e.g., northern Europe, such as Scandinavia and Finland), where the length of the active season is reduced by as much as two-thirds, these snakes are active throughout the day and are able to take advantage of every warm hour in order to complete the necessary portions of their life cycle.
While contemporary academics take deadly wine and cheese colloquia as a necessary, albeit baneful, portion of their service to the Academy, the Riesling was never sourer nor the Handkäse (and Schweineschmalz) quite so... memorable... as during such Wolfenbüttel gatherings.
In both cases, a rooftop network of production could directly supply a portion of a necessary resource – either food or electricity – to the local community while concurrently reducing the burden on the environment.
His view was that when people unjustly harm others, a portion of their estates may be used to make reparation to the people they harmed, and as a necessary result their children cannot inherit that portion of their estates.
If greater visualization is necessary, a portion of the inferior spinous process can be removed.
If a teacher finds a portion in the goal map where modification is necessary, he/she is allowed to modify the portion in the goal map modification phase.
The number of fibers necessary to cover an adequate portion of a small animal is thus quite modest.
Tumors were then removed, measured, weighed, photographed and sectioned if necessary, and portions were placed in Millonig's 10% buffered formalin (Surgipath, Richmond, IL) for 24 hours prior to being placed in 70% ethanol.
