The routine is : warm-up with one set and change set every time you play.
There are four sets so in four times you train for a large part of piano difficulties.
The first set explores many ways to play notes one by one : with different fingers or with the same finger, jumps, extensions, thumbs under other fingers, substitutions, ornaments etc. It develops the agility of each finger.
Set 2 : two notes at the same time
The second set is very similar to the first one but here you play two notes simultenaously. Beautiful thirds and sixths, powerful octaves and other intervals.
The third set is twofold. First category of exercices develop the independence of fingers : some notes are kept while others are played. In the second category more and more notes are played simultaneously until you reach 4, even 5, notes chords and arpeggios.
The last set contains a selection of scales and arpeggios. Why to play scales and arpeggios ?
Because they are everywhere in music. Just play a piece of melody with 3 notes and you see it’s very often a part of a scale or a chord.
This set contains the most simple form of scales and arpeggios but also, broken ones, in thirds, sixths, octaves, in chords etc. To finish I gathered different chords for your harmonic hear.
A few comments
Play hands separately, unless indicated, because it’s easier.
Play not fast, focus on the quality of the sound and relax. Try to do a minimum of movement, ideally only the right muscles at the right moment.
Easier exercises and most common ways of playing are at the beginning of the sets.
It takes between 10 and 15 minutes for one set. But depending of your experience as a pianist and knowledge of the exercises, it can be longer. Then I suggest you stop after 10 to 15 minutes. The next time you play the set, restart from the beginning and you will be able to add one or two more exercises. Progressively you will be able to complete the set in less than 15 minutes.
Once you know the sets as written in C you can test another scale without changing fingerings. For instance if you play a music in G minor why not play the sets in G minor as well. It’s not so difficult because exercises are short.
If you are not motivated to play a set do something different. For instance with sight-reading or improvising or playing a piece you know.
If you have only 15 minutes to play piano, don’t play a set, just play music.
Ask your piano teacher some advices about the best way to play the exercises.