The phrase "increase mastery" is correct and usable in written English.
You can use it when discussing the improvement of skills or knowledge in a particular area.
Example: "To excel in this field, it is essential to engage in continuous learning to increase mastery of the subject."
Alternatives: "enhance proficiency" or "boost expertise."
Ms. Ephraim got the idea for the Great Pasta Race back in 1995 at a summer program in mathematics and science run by the Project to Increase Mastery of Mathematics and Science at Wesleyan University.
In particular, interventions to reduce depression, increase mastery and improve active coping are all indicated.
To compare their performance with goals and to increase mastery experience (BCT 2.3), participants were prompted to review and visualize their past successes ('which success experiences had you in washing your hands regularly? Please write here').
The evolution of Truffaut's way of working depended, at least to some extent, on his increasing mastery of technique.
Iron tools and weapons greatly increased mastery over both man and nature and, together with food production, promoted population growth.
This very fragmentary decoration has yielded important information about a stage of increasing mastery in the handling of the medium.
Portraits, nudes, and genre scenes have occupied most of his attention so far, and several critics have noted Currin's increasing mastery of these antique forms.
The arrival of a neophyte justice coupled with Chief Justice Roberts's increasing mastery of the judicial machinery foreshadow a widening gap between the Democratic-led political branches and the Supreme Court.
At all periods in Brahms's work one finds a great variety of expression from the subtly humorous to the tragic but his larger works show an increasing mastery of movement and an ever-greater economy and concentration.
Mauriac showed increasing mastery in Le Désert de l'amour (1925; The Desert of Love) and in Thérèse Desqueyroux (1927; Thérèse), whose heroine is driven to attempt the murder of her husband to escape her suffocating life.
A bridge between the Baroque opera seria — with its heroes, themes of antiquity and recitative — and the theatrical power of his later works, "Idomeneo" demonstrates his increasing mastery of orchestral color, which, for the first time in his operas, includes clarinets.
