SCALES STARTING OFF FROM VARIOUS DEGREES

In actual musical practice you don't always find scales that start off from the tonic, so as well as doing traditional scale practice, it is also logical to study starting off from various degrees.
This is because beginning a scale from another degree implies a change of fingering, so if you don't study the various combinations you'll be caught out. Besides, getting used to starting off from any degree whatsoever reinforces mastery of tonality, preparing the mind and hands for any succession in any tone.