Is ritual necessary for magick?

Necessity it the wrong word. For the untrained it may be necessary.

It's like walking after you've come out of a coma. Ritual is a Crutch. A necessary crutch. However, at a certain point, you don't need crutches any more. At a certain point, the crutches are even an encumbrance.

Although beyond that metaphor Ritual serves one more function. Community Foci. Wherein even here the metaphor does apply. It's like running in a sack race (Which is where two people stick one leg in a sack and try to run together). But, still, even then, Imagine everyone in a circle with both legs in seperate sack. Now, hit music and start dancing!

Come to think of it, that's not a bad idea for a ritual for a Coven/whatever.

I say "No, never", but I give this answer in an agnostic and polemical spirit. Here are my first exploratory arguments on the matter.

First of all, what is "ritual", and what is "magick"? If magic is of the materially manipulative sort, then a question arises. Could one have gotten the result by other means? For instance, one invokes a spirit to the end of financial independence, and the result might be a flush job offer, an inheritance, an opportunity to participate in a bank heist, or what have you. The invocation may or may not have a causal connection to these outcomes, but there are certainly other ways to become financially independent, such as working and saving, or doing one's market research and then starting a business. Insofar as success is the sole criterion of magic, it is clear, in this case, that ritual is not necessary to do magic.

It is an empirical question whether there are other manipulative ends that one could satisfy only by ritual. I will not bother to list all ends, for such a list would be infinite, or at least very large. In lieu of a list, consider an objective that is totally outlandish, e.g. to dim the sun. Even assuming that the will of an entire magical corps would be sufficient to accomplish this end (no small assumption), this end is nonetheless also imaginable by technology yet to be seen, as in the sci-fi of Vernor Vinge. It is enough to say that ritual is unlikely to have sole claim to any given material manipulation.

Manipulative magic contrasts with "developmental" magick. (If there are other classes of magic, I leave them to others to address.) Developmental magic is roughly what most people have in mind when thinking of spirituality. On this topic, Crowley is clear, if not authoritative (MTP, chapter XIV):

But at least there is no need of any special device "ad hoc" to effect contact between the Circle and the Triangle. Operations of this class are therefore often successful, even when the Magician has little or no technical knowledge of Magick. Almost any duffer can "pull himself together", devote himself to study, break off a bad habit, or conquer a cowardice. This class of work, although the easiest, is yet the most important; for it includes initiation itself in its highest sense. It extends to the Absolute in every dimension; it involves the most intimate analysis, and the most comprehensive synthesis. In a sense, it is the sole type of Magick either necessary or proper to the Adept; for it includes both the attainment of the Knowledge and Conversation of the Holy Guardian Angel, and the Adventure of the Abyss.