The phrase "a most useful" is correct and usable in written English.
It can be used to emphasize the high degree of usefulness of something, often in a formal or literary context.
Example: "The manual provided a most useful overview of the software's features."
Alternatives: "extremely helpful" or "very beneficial".
Well, for all that, that good man had so great a zeal for the advancement of learning, that he began it again, and went through with it to that perfection that he hath left it to us, a most useful work.
But it is a most useful slave, for it helps us understand and guide our competing passions.
The technique, however, is slow with low throughput, making it undesirable for use in drug discovery; an automated patch clamp that uses disposable devices would be a most useful outcome.
These findings suggest that MAMEF could be a most useful alternative to the DNA hybridization assays used today, especially with regard to substantially increasing both the assay rapidity and sensitivity.
The use of the dog ACL model in association with the complete set of functional methods used in the present study represents a most useful tool for the monitoring of pain and joint function in OA.
The Conference agreed that the study was a most useful stimulus for regional and national planning of land use and agricultural development, which could contribute to the timely formulation of population policies and overall development strategies.
It also allows people to save more money in tax-excluded health savings accounts, a change most useful to people with enough money to have savings.
Clearly, markers of group A are most useful as they provide evidence for both clinical relevance and involvement of immune function(s) by themselves.
Using Kibana gave us the flexibility to surface logs in a way that would be most useful to us.
And a definition is most useful if it provides what a scientist needs.
It was, he said: "A painter's most useful adjunct".
