By basic mastery, I mean here the ability to play ascending and descending half step throughout the entire range of the flute (low C to 4th octave C). For some, this may seem like a very advanced skill, but actually on the flute playing chromatic passages is relatively easy. Among the many difficulties that the flute presents, playing the chromatic scale is not one of them. These exercises are designed to gradually improve your ability to play the chromatic scale fluently, in longer and faster passages. The key here (as in any practice, for this matter) is to take your time, and not approach the exercises as a racing contest.
To a great extent, these exercises look similar to the famous De la Sonorité exercises by Marcel Moyse (commonly known as "long tones"), but with a different emphasis.
The Moyse exercises focus on evenness and homogeneity of tone. In these exercises you typically play a pair of half steps slowly, and sustain the second note. Here your focus should be on being confident about the notes you are about to play, and how to play them. For this purpose, in my exercises I suggest that you sustain the first note, and take this time to concentrate on the following note (or notes) you are about to play. Always work with your imagination. While you sustain the first note, imagine the following note as vividly as you can, and when it rings so loud in your mind's ear that you feel you simply must play, than go on and play it. If you think about, this ability to pre-hear music in your head in real time is the essence of making music. The path to mastery begins here, and once you enter this state of mind in your practice, these repetitive technical exercises become a universe of musical exploration.
With that in mind, it is important not to get too meticulous in your practice. Remember that perfection is the enemyof good. Don't get stuck on these pairs of half steps forever. When you feel you can play them with relative confidence and ease, move on to the next exercise, and then to the one after it and so forth. Eventually you will be able to play this:
Be flexible in your practice. On the one hand, listen to yourself very critically, and observe any uncertinties and "glitches" in your playing. On the other hand, take risks and move on. It is up to you to find the right balance between the two.