Gifted math students are often able to solve problems in their head without showing much, if any, work on paper. In fact, especially younger students, cannot show their work. Because they already know the answer, they have to work the problem backwards to show their work.
The purpose for showing work is to learn the process correctly. With continual practice, fluency or automation develops and over time, some of the steps are dropped because you "automatically" do them in your head. This is especially important on standardized tests where speed and accuracy are required. So, we don't want to frustrate a student by making them show every step when the end goal is to at least do some of it in your head.
If you have a gifted math student who really "gets math", is in 6th - 8th grade, working at least one grade level ahead, you do not have to require they show their work on homework problems (Practice Sets). However, if they get the problem wrong, they should follow the Corrections steps to re-learn and correct missed problems, including showing their work to solve the problem correctly on their correction notes.
Also, have the student show their work on the quizzes. There are only four questions on the quizzes so this should not be overwhelming or frustrating.